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    10g plsql slide 10g plsql slide Presentation Transcript

    • PL/SQL PL / SQL 7/5/12 7/5/12 1
    • PL/SQL Overview of PL/SQL Declaring Variables Writing Executable Statements Control Structures Composite Data Types Explicit Cursors Handling Exceptions Creating Procedures Creating Functions Creating Packages Oracle Supplied Packages Large OBjects Database Triggers Managing Dependencies 7/5/12 7/5/12 2
    • PL/SQL Overview of PL/SQL 7/5/12 7/5/12 3
    • PL/SQL PL / SQL  PL/SQL is the procedural extension to SQL with design feature of programming languages.  Data Manipulation and Query statements of SQL are included within procedural units of code.  Place reusable PL/SQL code in libraries to be shared between application to all users. 7/5/12 7/5/12 4
    • PL/SQL PL/SQL Versions Year Oracle PL/SQL Characteristics 1991 6 1.0 Programming Language 1992 7 2.0 Stored procedure, functions, packages, PL/SQL tables, DBMS_OUTPUT, DBMS_PIPE 1994 7.1 2.1 Programmer defined subtypes, DBMS_SQL, Stored functions inside SQL statement. 1995 7.3 2.3 UTL_FILE, Cursor variables, remote dependency 1997 8 8.0 LOB, Object-Oriented design, Advanced Queuing, Collections (VARRAY , nested table) 1998 8i 8.1 Native Dynamic SQL (EXECUTE IMMEDIATE), Support for Java, Autonomous Transaction 2000 9i R1 9.0 Native Compilation as C code, Inheritance in object types, multi-level collections, CASE expression 2002 9i R2 9.2 Oracle Text CTXXPATH, XML, index-by tables indexed by VARCHAR2, record-based DML, UTL_FILE (allows to copy, remove, and rename files). 2004 10g 10.0 Regular Expression, DBMS_WARNING package, BINARY_FLOAT, BINARY_DOUBLE, DBMS_LOB (128 TB), String literal. 7/5/12 7/5/12 5
    • PL/SQL * Block - The basic program unit in PL/SQL * Blocks contain sets of instructions to perform. (must contain one command) * You can declare variables. * You can program with Control Structures, IF-THEN-ELSE, LOOP... * Error handling functionality. * Nest sub-block inside large block to build powerful program. * Single line Comment -- * Multiple line Comments /* */ * A slash ( / ) runs the PL/SQL block. DECLARE (Optional) Variables, cursors, user-defined exception BEGIN (Mandatory) SQL & PL/SQL statements EXCEPTION (Optional) Actions to perform when error occur END; (Mandatory) / 7/5/12 7/5/12 6
    • PL/SQL Anonymous Procedure Function [DECLARE] PROCEDURE Name FUNCTION Name IS RETURN Datatype IS BEGIN BEGIN BEGIN -- statements -- statements -- statements RETURN [EXCEPTION] [EXCEPTION] [EXCEPTION] END; END; END; 7/5/12 7/5/12 7
    • PL/SQL  Oracle tools, like Developer, Oracle Forms have their own PL/SQL engine, which is independent of the engine present in the Oracle Server.  The engine filters out SQL statement and sends them individually to the SQL statement executor in the Oracle Server.  PL/SQL engine, processes remaining Procedural statements. PL / SQL engine PL/SQL PL/SQL Procedural statement block block executor SQL statement executor Oracle Server 7/5/12 7/5/12 8
    • PL/SQL Summary  PL/SQL  PL/SQL Block Structure  Block Types  PL/SQL Environment 7/5/12 7/5/12 9
    • PL/SQL Declaring Variables 7/5/12 7/5/12 10
    • PL/SQL Use of Variables  Temporary storage of data  Manipulation of stored values  Reusability Handling Variables  Declare and initialize variable in the declaration section.  Assign new values to variables in the executable section.  View results through output variables 7/5/12 7/5/12 11
    • PL/SQL Types of Variables PL / SQL  Scalar (hold a single value) - number, date, binary_integer, boolean (true, false, null), timestamp…  Composite (group of value) - records, cursors…  Reference (other program) - pointers  LOB (Large objects) - graphics, movies Non - PL / SQL  Bind and host variables - global values 7/5/12 7/5/12 12
    • PL/SQL * Follow naming conventions. * Declare one identifier per line. * Initialize identifiers by using the assignment operator ( := ) identifier [CONSTANT] datatype [NOT NULL] [ := | DEFAULT expr]; DECLARE v_hiredate DATE; v_deptno NUMBER(2) NOT NULL := 10; v_location VARCHAR2(12) := ‘Atlanta’; c_comm CONSTANT NUMBER := 1400; v_count BINARY_INTEGER := 0; v_total_sal NUMBER(9,2) := 0; v_orderdate DATE := SYSDATE + 7; v_valid BOOLEAN NOT NULL := TRUE; variables 7/5/12 7/5/12 13
    • PL/SQL * Declare variable according to : -- A database column definition -- Another previously declared variable identifier table.column_name%TYPE ; DECLARE v_name employees.last_name%TYPE ; v_balance NUMBER(7,2); v_min_balance v_balance%TYPE := 10; * Boolean (TRUE - FALSE - NULL) v_sal1 := 50000; DECLARE v_sal2 := 60000; v_flag BOOLEAN := FALSE; BEGIN v_sal1 < v_sal2 v_flag := TRUE; this evaluates to TRUE END; 7/5/12 7/5/12 14
    • PL/SQL • Large OBjects 4GB -- to store unstructured data (graphics, video, soundwave) -- CLOB Character Large OBject lengthy text -- BLOB Binary Large OBject Graphics, Photos -- BFILE Binary FILE Movie -- NCLOB National Language Other Language Character Large OBject 7/5/12 7/5/12 15
    • PL/SQL Summary  Variables / Identifiers - declared at declarative section  Declaring Variables  Types of Variables – SQL PL/SQL  %TYPE  LOB 7/5/12 7/5/12 16
    • PL/SQL Writing Executable Statements 7/5/12 7/5/12 17
    • PL/SQL DECLARE x NUMBER; y NUMBER; BEGIN ....... Scope of x , y DECLARE z NUMBER; BEGIN z := x ; Scope of z END; ....... y := z ; END; A block can look up to the enclosing block. A block cannot look down to the enclosed block. 7/5/12 7/5/12 18
    • PL/SQL The qualifier can be the label of the enclosing block. Qualify an identifier by using the block label prefix. <<abc>> DECLARE birthdate DATE; BEGIN DECLARE birthdate DATE; .. abc.birthdate := TO_DATE(‘03-AUG-2004’,’DD-MON-YYYY’); END; .. END; 7/5/12 7/5/12 19
    • PL/SQL  To reference a Bind Variable, prefix with colon ( : ) VARIABLE g_monthly_sal NUMBER DEFINE p_annual_sal = 5000 SET VERIFY OFF DECLARE v_sal NUMBER(9,2) := &p_annual_sal; BEGIN :g_monthly_sal := v_sal / 12; END; / PRINT g_monthly_sal 7/5/12 7/5/12 20
    • PL/SQL * Retrieve data from the database with a SELECT statement. * Queries must return only one row. SELECT select_list INTO {variable_name[, variable_name]... | record_name} FROM table [WHERE condition]; * Retrieve the department no and location no, for department Sales. DECLARE v_deptno NUMBER(4); v_locid NUMBER(4); BEGIN SELECT department_id, location_id INTO v_deptno, v_locid FROM departments WHERE department_name = ‘Sales’; END; 7/5/12 7/5/12 21
    • PL/SQL  An Oracle-supplied packaged procedure  To display data to screen  Enable with SET SERVEROUTPUT ON SET SERVEROUTPUT ON DEFINE p_annual_sal = 6000 DECLARE v_sal NUMBER(9,2) := p_annual_sal; BEGIN v_sal := v_sal/12; DBMS_OUTPUT.PUT_LINE (‘The monthly salary is’ || TO_CHAR(v_sal)); END; / 7/5/12 7/5/12 22
    • PL/SQL * Display the sum of the salaries for all employees in the specified department. SET SERVEROUTPUT ON DECLARE v_sum_sal NUMBER(10,2); BEGIN SELECT sum(salary) INTO v_sum_sal FROM employees WHERE department_id = 30; DBMS_OUTPUT.PUT_LINE(‘The sum salary is ‘ || TO_CHAR(v_sum_sal)); END; / .. .. BEGIN Analyze the result SELECT salary INTO v_sum_sal Why ? FROM employees WHERE department_id = 30; 7/5/12 7/5/12 23
    • PL/SQL * The following DELETE statement removes all employees, where last name is not just ‘King’, because Oracle assumes that both last_name(s) in the WHERE clause refer to the database column. DECLARE last_name VARCHAR2(25) := ‘King’; BEGIN DELETE FROM emp_copy WHERE last_name = last_name ; END; 7/5/12 7/5/12 24
    • PL/SQL SET SERVEROUTPUT ON DECLARE v_name VARCHAR2(10) := ‘Reynardo’; v_address VARCHAR2(12) := ‘#9, MG Road’; v_city VARCHAR2(10) := ‘Bangalore’; v_zip VARCHAR2(7) := ‘560 006’; BEGIN DBMS_OUTPUT.PUT_LINE(v_name || CHR(10) || v_address || CHR(10) || v_city || CHR(10) || v_zip); END; v_ename := LOWER(v_ename); v_date := TO_DATE(‘January 12, 2005’, ‘Month DD, YYYY’); 7/5/12 7/5/12 25
    • PL/SQL BEGIN INSERT INTO employees (employee_id, first_name, last_name, email, hire_date, job_id, salary) VALUES ( 27 , ‘Ruth’, ‘Cores’, ‘RCORES’, sysdate, ‘AD_ASST’ 9000); END; DECLARE v_sal_inc employees.salary%TYPE := 800; BEGIN UPDATE employees SET salary = salary + v_sal_inc WHERE job_id = ‘ST_CLERK’; COMMIT; END; DECLARE v_deptno employees.department_id%TYPE := 80; BEGIN DELETE FROM employees WHERE department_id = v_deptno ; END; 7/5/12 7/5/12 26
    • PL/SQL * Cursor is a private SQL work area for each user. * Two Types : Implicit Cursor - Automatically created if any SQL statement is executed. Explicit Cursor - Can Create by programmer. Attributes are used to test the outcome of the result. SQL%ROWCOUNT Number of rows affected by the recent SQL statement SQL%FOUND Boolean attribute that evaluates TRUE if the recent SQL statement affects one or more rows. SQL%NOTFOUND Boolean attribute that evaluates TRUE if the recent SQL statement does not affects any rows. SQL%ISOPEN Always evaluates FALSE because, implicit cursors are closed immediately after they are executed. 7/5/12 7/5/12 27
    • PL/SQL VARIABLE rows_deleted VARCHAR2(30) DECLARE v_eid employees.employee_id%TYPE := 176; BEGIN DELETE FROM employees WHERE employee_id = v_eid; :rows_deleted := (SQL%ROWCOUNT || ‘ rows deleted.’); END; / PRINT rows_deleted 7/5/12 7/5/12 28
    • PL/SQL DECLARE v_weight NUMBER(3) := 600; v_message VARCHAR2(99) := ‘ Product 10012’; BEGIN DECLARE v_weight NUMBER(3) := 1; v_message VARCHAR2(90) := ‘Product 11001’; v_new_locn VARCHAR2(50) := ‘Europe’; BEGIN v_weight := v_weight + 1; v_new_locn := ‘Western ‘ || v_new_locn; 1 END; v_weight := v_weight + 1; v_message := v_message || ‘ is in stock’; v_new_locn := ‘Western ‘ || v_new_locn; 2 END; The value of V_WEIGHT at position 1 -> 2 The value of V_NEW_LOCN at position 1 -> Western Europe The value of V_WEIGHT at position 2 -> 601 The value of V_MESSAGE at position 2 -> Product 10012 is in stock The value of V_NEW_LOCN at position 2 -> Illegal because, not visible outside the sub-block 7/5/12 7/5/12 29
    • PL/SQL Class Exercise 1 <<abc>> DECLARE v_sal NUMBER(7,2) := 60000; v_comm NUMBER(7,2) := v_sal * 0.20; v_message VARCHAR2(90) := ‘ eligible for commission ’; BEGIN DECLARE v_sal NUMBER(7,2) := 50000; v_comm NUMBER(7,2) := 0; v_total_comp NUMBER(7,2) := v_sal * v_comm; BEGIN v_message := ‘CLERK not ’|| v_message; abc.v_comm := v_sal * 0.30; 1 END; v_message := ‘SALESMAN’ || v_message; 2 END; The value of V_MESSAGE at position 1 The value of V_TOTAL_COMP at position 2 The value of V_COMM at position 1 The value of V_COMM at position 2 The value of ABC.V_COMM at position 1 The value of V_MESSAGE at position 2 7/5/12 7/5/12 30
    • PL/SQL Summary  Nested Blocks and Scope Variables  Qualify and Identifier  SELECT statement in PL/SQL  Using Bind Variable  DBMS_OUTPUT.PUT_LINE  Retrieve Data  Naming Convention  Functions in PL/SQL  Insert / Update / Delete  Cursors 7/5/12 7/5/12 31
    • PL/SQL Control Structures 7/5/12 7/5/12 32
    • PL/SQL * You can change the logical execution of statements using IF statements and LOOP control structures IF condition THEN statements; [ELSIF condition THEN statements;] [ELSE statements;] END IF; Eg., If the employee name is Vargas, set job id to SA_REP and set department number to 80 IF UPPER(v_last_name) = ‘VARGAS’ THEN v_job := ‘SA_REP’ v_deptno := 80; END IF; 7/5/12 7/5/12 33
    • PL/SQL Eg., If the last name is Vargas and the salary is more than 6500, Set the department number to 60. IF v_ename = ‘Vargas’ AND salary > 6500 THEN v_deptno := 60; END IF; .. Set a Boolean flag to TRUE if the hire date is greater than Five years; other wise, set the Boolean flag to FALSE. DECLARE v_hire_date DATE := ’12-DEC-1990’; v_five_years BOOLEAN; BEGIN IF MONTHS_BETWEEN(sysdate,v_hire_date)/12 > 5 THEN v_five_years := TRUE; ELSE v_five_years := FALSE; END IF; END; / 7/5/12 7/5/12 34
    • PL/SQL IF condition1 THEN statements1; ELSIF condition2 THEN statements2; ELSE statements3; END IF; Determine an employee’s bonus based upon the employee’s department. ... IF v_deptno = 10 THEN v_bonus := 5000; ELSIF v_deptno = 80 THEN v_bonus := 7500; ELSE v_bonus := 2000; ... END IF; 7/5/12 7/5/12 35
    • PL/SQL CASE expression selects a result and returns it. SET SERVEROUTPUT ON DECLARE v_grade CHAR(1) := ‘A’; v_appraisal VARCHAR2(20); BEGIN v_appraisal := CASE v_grade WHEN ‘A’ THEN ‘Excellent’ WHEN ‘B’ THEN ‘Very Good’ WHEN ‘C’ THEN ‘Good’ ELSE ‘No such grade’ END; DBMS_OUTPUT.PUT_LINE (‘Grade: ’ || v_grade || ‘ Appraisal’ || v_appraisal); END; / 7/5/12 7/5/12 36
    • PL/SQL 7/5/12 7/5/12 37
    • PL/SQL • LOOPs repeat a statement or sequence of statements multiple times. • Types of LOOP Basic LOOP - Perform repetitive actions without overall conditions. FOR loop - Perform iterative control of actions based on count. WHILE loop - perform iterative control based on a condition. 7/5/12 7/5/12 38
    • PL/SQL • A basic LOOP allows execution of its statements atleast once, even if the condition already met upon entering the loop. LOOP statement1; EXIT [WHEN condition]; END LOOP; DECLARE v_country_id locations.country_id%TYPE := ‘CA’; v_location_id locations.location_id%TYPE; v_counter NUMBER(2) := 1; v_city locations.city%TYPE := ‘Montreal’; BEGIN SELECT MAX(location_id) INTO v_location_id FROM locations WHERE country_id = v_country_id; LOOP INSERT INTO locations(location_id, city, country_id) VALUES((v_location_id + v_counter),v_city,v_country_id); v_counter := v_counter + 1; EXIT WHEN v_counter > 3; END LOOP; END; 7/5/12 7/5/12 39
    • PL/SQL • A WHILE Loop repeats sequence of statements until the controlling condition is no longer TRUE. WHILE condition LOOP statement1..; END LOOP; DECLARE v_country_id locations.country_id%TYPE := ‘CA’; v_location_id locations.location_id%TYPE; v_counter NUMBER(2) := 1; v_city locations.city%TYPE := ‘Washington’; BEGIN SELECT MAX(location_id) INTO v_location_id FROM locations WHERE country_id = v_country_id; WHILE v_counter <= 3 LOOP INSERT INTO locations(location_id, country_id) VALUES((v_location_id + v_counter),v_city,v_country_id); v_counter := v_counter + 1; END LOOP; END; 7/5/12 7/5/12 40
    • PL/SQL • A FOR Loop is used to test for the number of iterations. FOR counter IN [REVERSE] lower_bound..upper_bound LOOP statement1..; statement2..; Implicitly j IN -5..5 declared k IN REVERSE first..last END LOOP; step IN 0..TRUNC(high/low) * 2 DECLARE v_country_id locations.country_id%TYPE := ‘CA’; v_location_id locations.location_id%TYPE; v_city locations.city%TYPE := ‘Paris’; BEGIN SELECT MAX(location_id) INTO v_location_id FROM locations WHERE country_id = v_country_id; FOR i IN 1..3 LOOP INSERT INTO locations(location_id, country_id) VALUES((v_location_id + i), v_city, v_country_id); v_counter := v_counter + 1; END LOOP; END; 7/5/12 7/5/12 41
    • PL/SQL Specify a different increment (5 instead of 1 for example). Inside the FOR loop, simply multiply each reference to the loop counter by the new increment. In the following example, you assign todays date to elements 5, 10, and 15 of an index-by table: DECLARE TYPE DateList IS TABLE OF DATE INDEX BY BINARY_INTEGER; dates DateList; k CONSTANT INTEGER := 5; -- set new increment BEGIN FOR j IN 1..3 LOOP dates(j*k) := SYSDATE; -- multiply loop counter by increment END LOOP; ... END; FOR ctr IN 1..10 LOOP IF NOT finished THEN INSERT INTO ... VALUES (ctr, ...); -- OK factor := ctr * 2; -- OK ELSE ctr := 10; -- not allowed END IF; END LOOP; 7/5/12 7/5/12 42
    • PL/SQL • Nest loops to multiple levels. • Use labels to distinguish between blocks and loops. • Exit the outer loop with the EXIT statement that references the label. .. .. .. BEGIN <<Outer_loop>> LOOP v_counter := v_counter + 1; EXIT WHEN v_counter > 10; -- leaves both loops <<Inner_loop>> LOOP ... EXIT Outer_loop WHEN total_done = ‘YES’; -- leaves both loops EXIT WHEN inner_done = ‘YES’; -- leaves inner loop only .. .. END LOOP Inner_loop; .. .. END LOOP Outer_loop; END; 7/5/12 7/5/12 43
    • PL/SQL • Create the MESSAGES table with column results varchar2(60) • Insert the numbers 1 to 10 excluding 6 and 8 • Commit before the end of the block BEGIN FOR i IN 1..10 LOOP IF i = 6 or i = 8 THEN null; ELSE INSERT INTO messages(results) VALUES (i); END IF; COMMIT; END LOOP; END; / 7/5/12 7/5/12 44
    • PL/SQL Summary LOOP IF condition1 THEN statement1; statements1; EXIT [WHEN condition]; ELSIF condition2 THEN END LOOP; statements2; ELSE statements3; END IF; CASE WHILE condition LOOP statement1..; BOOLEAN END LOOP; FOR counter IN [REVERSE] lower_bound..upper_bound LOOP statement1..; statement2..; END LOOP; 7/5/12 7/5/12 45
    • PL/SQL Composite Data Types 7/5/12 7/5/12 46
    • PL/SQL * Declare a variable according to the collection of columns in a database table or view. * Prefix %ROWTYPE with the database table. * Fields in the record take their names and data types from the columns of the table or view DEFINE employee_no = 124 DECLARE emp_rec employees%ROWTYPE; BEGIN SELECT * INTO emp_rec FROM employees WHERE employee_id = &employee_no; INSERT INTO retired_emps(empno, ename, job, mgr, hiredate, leavedate, sal, comm, deptno) VALUES (emp_rec.employee_id, emp_rec.last_name, emp_rec.job_id, emp_rec.manager_id, emp_rec.hire_date, SYSDATE, emp_rec.salary, emp_rec.commission_pct, emp_rec.department_id); COMMIT; END; / 7/5/12 7/5/12 47
    • PL/SQL Write a PL/SQL block to print information about a given country DEFINE p_countryid = CA DECLARE country_record countries%ROWTYPE; BEGIN SELECT * INTO country_record FROM countries WHERE country_id = UPPER(‘&p_countryid’); DBMS_OUTPUT.PUT_LINE ( ‘ Country Id: ‘|| country_record.country_id || ‘ Country Name: ‘|| country_record.country_name|| ‘ Region: ‘|| country_record.region_id); END; / 7/5/12 7/5/12 48
    • PL/SQL Explicit Cursors 7/5/12 7/5/12 49
    • PL/SQL  Every SQL statement executed by the Oracle Server has an individual cursor associated with it. Implicit Cursor : Declared for all DML and PL/SQL SELECT statements. Explicit Cursor : Declared and named by the programmer.  Use CURSOR to individually process each row returned by a multiple-row SELECT Statement.  The set of rows returned by a multiple-row query is called active set. No Yes DECLARE OPEN FETCH EMPTY? CLOSE Create a Identify the Lead the Test for existing Release the named SQL active set current row rows active set. area into variables Return to FETCH if rows are found 7/5/12 7/5/12 50
    • PL/SQL * Retrieve the first 10 employees one by one. SET SERVEROUTPUT ON DECLARE v_empno employees.employee_id%TYPE; v_ename employees.last_name%TYPE; CURSOR emp_cursor IS SELECT employee_id, last_name FROM employees; BEGIN OPEN emp_cursor; FOR i IN 1..10 LOOP FETCH emp_cursor INTO v_empno, v_ename; DBMS_OUTPUT.PUT_LINE(TO_CHAR(v_empno)||’ ‘||v_ename); END LOOP; CLOSE emp_cursor; END; 7/5/12 7/5/12 51
    • PL/SQL cname%ROWCOUNT Number Evaluates to the total number of rows returned so for cname%FOUND Boolean Evaluates to TRUE if the most recent fetch returns a row. cname%NOTFOUND Boolean Evaluates to TRUE if the most recent fetch does not return a row. cname%ISOPEN Boolean Evaluates TRUE if the cursor is open IF NOT emp_cursor%ISOPEN THEN LOOP OPEN emp_cusor; FETCH c1 INTO my_ename, my_sal; END IF; LOOP EXIT WHEN c1%NOTFOUND; FETCH emp_cursor.. .. .. .. END LOOP; LOOP FETCH c1 INTO my_deptno; IF c1%ROWCOUNT > 10 THEN .. .. END IF; .. .. END LOOP; 7/5/12 7/5/12 52
    • PL/SQL * Retrieve the first 10 employees one by one by using attributes. SET SERVEROUTPUT ON DECLARE v_empno employees.employee_id%TYPE; v_ename employees.last_name%TYPE; CURSOR emp_cursor IS SELECT employee_id, last_name FROM employees; BEGIN OPEN emp_cursor; LOOP FETCH emp_cursor INTO v_empno, v_ename; EXIT WHEN emp_cursor%ROWCOUNT > 10 OR emp_cursor%NOTFOUND; DBMS_OUTPUT.PUT_LINE(TO_CHAR(v_empno)||’ ‘||v_ename); END LOOP; CLOSE emp_cursor; END; 7/5/12 7/5/12 53
    • PL/SQL * Process the rows of the active set by fetching values into PL/SQL RECORD. Populate to the table temp_list. DECLARE CURSOR emp_cursor IS SELECT employee_id, last_name FROM employees; emp_record emp_cursor%ROWTYPE; BEGIN OPEN emp_cursor; LOOP FETCH emp_cursor INTO emp_record; EXIT WHEN emp_cursor%NOTFOUND; INSERT INTO temp_list (emp_id, ename) VALUES (emp_record.employee_id, emp_record.last_name); END LOOP; COMMIT; CLOSE emp_cursor; END; 7/5/12 7/5/12 54
    • PL/SQL * Implicit Open, Fetch, and Close occurs The record is implicitly declared. Retrieve employee one by one who is working in department 80 SET SERVEROUTPUT ON DECLARE CURSOR emp_cursor IS SELECT last_name, department_id FROM employees; BEGIN FOR emp_record IN emp_cursor LOOP -- implicit open fetch occur IF emp_record.department_id = 80 THEN DBMS_OUTPUT.PUT_LINE(‘Employee ‘ || emp_record.last_name || ‘ works in the Sales Dept.‘); END IF; END LOOP; -- implicit close END; 7/5/12 7/5/12 55
    • PL/SQL * No need to declare the cursor, if FOR loop is used Same result as previous Slide : Retrieve employee one by one who is working in department 80 SET SERVEROUTPUT ON BEGIN FOR emp_record IN (SELECT last_name, department_id FROM employees) LOOP -- implicit open fetch occur IF emp_record.department_id = 80 THEN DBMS_OUTPUT.PUT_LINE(‘Employee ‘ || emp_record.last_name || ‘ works in the Sales Dept.‘); END IF; END LOOP; -- implicit close END; 7/5/12 7/5/12 56
    • PL/SQL * Pass parameter values to a cursor using WHERE, and Open an explicit cursor several times with a different times with the different active set each time. SET SERVEROUTPUT ON DECLARE CURSOR emp_cursor (p_dno NUMBER) IS SELECT employee_id, last_name FROM employees WHERE department_id = p_dno; BEGIN FOR emp_record IN emp_cursor(50) LOOP DBMS_OUTPUT.PUT_LINE(‘Employee ‘ || emp_record.employee_id||’ ‘|| emp_record.last_name || ‘ works in 50‘); END LOOP; FOR emp_record IN emp_cursor(60) LOOP DBMS_OUTPUT.PUT_LINE(‘Employee ‘ || emp_record.employee_id||’ ‘|| emp_record.last_name || ‘ works in 60‘); END LOOP; END; / 7/5/12 7/5/12 57
    • PL/SQL FOR UPDATE Clause -- Use explicit locking to deny access for the duration of a transaction. -- Lock the rows before the update or delete. -- NOWAIT keyword tells not to wait if requested rows have been locked by another user. WHERE CURRENT OF cursor; To reference the current row from an explicit cursor. DECLARE CURSOR sal_cursor IS SELECT e.department_id, employee_id, last_name, salary FROM employees e, departments d WHERE d.department_id = e.department_id AND d.department_id=60 FOR UPDATE OF salary NOWAIT; BEGIN FOR emp_record IN sal_cursor LOOP IF emp_record.salary < 5000 THEN UPDATE employees SET salary = emp_record.salary * 1.10 WHERE CURRENT OF sal_cursor ; END IF; END LOOP; END; 7/5/12 7/5/12 58
    • PL/SQL Summary  Use CURSOR to individually process each row returned by a multiple-row SELECT Statement.  Implicit Cursor : Declared for all DML and PL/SQL SELECT statements. Explicit Cursor : Declared and named by the programmer.  Using Attributes  Fetching values into PL/SQL RECORD  FOR loop - Implicit Open, Fetch, and Close occurs The record is implicitly declared.  Cursor with Parameters.  FOR UPDATE OF . . NOWAIT WHERE CURRENT OF 7/5/12 7/5/12 59
    • PL/SQL Handling Exceptions 7/5/12 7/5/12 60
    • PL/SQL  An exception is an identifier in the PL/SQL that is raised during execution.  How it is raised ? [DECLARE] - An Oracle error occurs. - You raise it explicitly. BEGIN Exception/Error is Raised  How do you handle it ? - Trap it with handler. EXCEPTION Error is Trapped - Propagate it to the calling environment. END;  Types of Exceptions User activity Predefined apprx. 20 errors ( < -20000 ) Declared Raised eg. ORA-01422 TOO_MANY_ROWS NO NO Non-Predefined Any other standard ( < -20000 ) YES NO Oracle Server Error User Defined A condition that the (-20000 and -20999) YES YES developer determine is abnormal 7/5/12 7/5/12 61
    • PL/SQL DEFINE p_dept_desc = ‘Information Technology’ DEFINE p_dept_no = 300 SET SERVEROUTPUT ON DECLARE e_invalid_department EXCEPTION; BEGIN UPDATE departments SET department_name = ‘&p_dept_desc’ WHERE department_id = &p_dept_no ; IF SQL%NOTFOUND THEN RAISE e_invalid_department; END IF; COMMIT; EXCEPTION WHEN e_invalid_department THEN DBMS_OUTPUT.PUT_LINE(‘No such department id.’); END; 7/5/12 7/5/12 62
    • PL/SQL  Reference the standard name in the exception handling routine.  Sample Pre-defined exceptions NO_DATA_FOUND TOO_MANY_ROWS INVALID_CURSOR ZERO_DIVIDE * The following block produces error with the execution part, the error is trapped in the exception part. SET SERVEROUTPUT ON DECLARE v_deptno NUMBER(4); v_loc_id NUMBER(4); BEGIN SELECT department_id, location_id INTO v_deptno, v_loc_id FROM departments; EXCEPTION WHEN TOO_MANY_ROWS THEN --traps pre-defined error DBMS_OUTPUT.PUT_LINE(‘fetches more than one row, use cursor…’); WHEN OTHERS THEN --traps errors which is not handled by above exception DBMS_OUTPUT.PUT_LINE(‘this error not trapped by exception..’); END; 7/5/12 7/5/12 63
    • PL/SQL  PRAGMA (pseudo-instructions) is the keyword that signifies that the statement is a compiler directive, which is not processed when the PL/SQL block is executed.  PRAGMA EXCEPTION_INIT(exception,oracle_error_number);  Trap for Oracle Server error number -2292, an integrity constraint violation DEFINE p_deptno = 10 SET SERVEROUTPUT ON DECLARE e_emps_remaining EXCEPTION; PRAGMA EXCEPTION_INIT (e_emps_remaining, -2292); BEGIN DELETE FROM departments WHERE department_id = &p_deptno; COMMIT; EXCEPTION WHEN e_emps_remaining THEN --traps non-predefined error DBMS_OUTPUT.PUT_LINE(‘Cannot remove dept ‘|| TO_CHAR(&p_deptno) || ‘. Employees exists. ‘); END; 7/5/12 7/5/12 64
    • PL/SQL  SQLCODE Returns the numeric value for the error code. SQLERRM Returns the message associated with the error number. SET SERVEROUTPUT ON DECLARE v_deptno NUMBER(4); v_loc_id NUMBER(4); err_num NUMBER; err_msg VARCHAR2(100); BEGIN SELECT department_id, location_id INTO v_deptno, v_loc_id FROM departments; EXCEPTION WHEN ZERO_DIVIDE THEN --traps pre-defined error DBMS_OUTPUT.PUT_LINE(‘number is divided by zero…’); WHEN OTHERS THEN --traps errors with Error Message err_num := SQLCODE; err_msg := SUBSTR(SQLERRM,1,100); DBMS_OUTPUT.PUT_LINE(‘Trapped Error: ‘|| err_msg ); END; 7/5/12 7/5/12 65
    • PL/SQL Example DECLARE .. .. e_no_rows EXCEPTION; e_integrity EXCEPTION; PRAGMA EXCEPTION_INIT(e_integrity, -2292); BEGIN FOR c_record IN emp_cursor LOOP BEGIN SELECT .. .. ; Sub-block can handle UPDATE .. .. ; Block without an exception or pass IF SQL%NOTFOUND THEN the exception. the exception to the RAISE e_no_rows; enclosing block. END IF; END; END LOOP; EXCEPTION WHEN e_integrity THEN .. .. WHEN e_no_rows THEN .. .. Error Trapped. END; 7/5/12 7/5/12 66
    • PL/SQL Summary  Exception Types Predefined Oracle Server error Non-predefined Oracle Server error User-defined error  Exception Trapping  Exception Handling Trap the exception within the PL/SQL block Propagate the exception 7/5/12 7/5/12 67
    • PL/SQL Creating Procedures 7/5/12 7/5/12 68
    • PL/SQL <header> IS | AS Declaration section .. .. BEGIN .. .. EXCEPTION .. .. A Subprogram : END; Is a named PL/SQL block that can accept parameters and be invoked from a calling environment. Procedure - that performs an action Function - that computes a value Provides easy maintenance , improved data security, improved performance. 7/5/12 7/5/12 69
    • PL/SQL  A procedure is a type of named subprogram that performs an action.  Procedure accepts parameters / arguments for further calls.  A procedure can be stored in the database, as a schema object, for repeated execution. Procedure IN parameter (default) Calling environment OUT parameter IN OUT parameter <header> IS | AS .. .. BEGIN .. .. EXCEPTION .. .. END; 7/5/12 7/5/12 70
    • PL/SQL CREATE OR REPLACE PROCEDURE raise_salary (p_id IN employees.employee_id%TYPE) IS BEGIN UPDATE employees SET salary = salary * 1.20 WHERE employee_id = p_id; 176 p_id END raise_salary; / EXECUTE raise_salary(176); Actual parameters Formal parameters Formal parameters : Variables declared in the parameter list of a subprogram specification. CREATE PROCEDURE raise_sal (p_id NUMBER, p_amount NUMBER) .. .. END raise_sal; Actual parameters : Variables or expressions referenced in the parameter list of a subprogram call. raise_sal(v_id,200) 7/5/12 7/5/12 71
    • PL/SQL CREATE OR REPLACE PROCEDURE query_emp (p_id IN employees.employee_id%TYPE, p_name OUT employees.last_name%TYPE, p_sal OUT employees.salary%TYPE) IS BEGIN 171 p_id SELECT last_name, salary INTO p_name, p_sal SMITH p_name FROM employees WHERE employee_id = p_id; END query_emp; 7400 p_sal / VARIABLE g_name VARCHAR2(20) VARIABLE g_sal NUMBER EXECUTE query_emp(171, :g_name, :g_sal) PRINT g_name g_sal 7/5/12 7/5/12 72
    • PL/SQL ‘8006330575’ ‘(800)633-0575’ p_phone_no CREATE OR REPLACE PROCEDURE format_phone (p_phone_no IN OUT VARCHAR2) IS BEGIN p_phone_no := ‘(‘ || SUBSTR(p_phone_no,1,3) || ‘)’ || SUBSTR(p_phone_no,4,3) || ‘-’ || SUBSTR(p_phone_no,7) ; END format_phone; / VARIABLE g_ph_no VARCHAR2(15) BEGIN :g_ph_no := ‘8006330575’; END; / PRINT g_ph_no EXECUTE format_phone(:g_ph_no) PRINT g_ph_no 7/5/12 7/5/12 73
    • PL/SQL CREATE OR REPLACE PROCEDURE add_dept (p_name IN departments.department_name%TYPE DEFAULT ‘unknown’, p_loc IN departments.location_id%TYPE DEFAULT 1700 ) IS BEGIN INSERT INTO departments(department_id, department_name, location_id) VALUES(dept_seq.NEXTVAL, p_name, p_loc); END add_dept; / Note : OUT and IN OUT parameters are not permitted to have DEFAULT values. 7/5/12 7/5/12 74
    • PL/SQL BEGIN add_dept; add_dept(‘TRAINING’, 2500); Positional add_dept(p_loc =>2400, p_name =>‘EDUCATION’); Named add_dept(p_loc =>1200); Combination END; / SELECT department_id, department_name, location_id FROM departments; Consider dept_seq.NEXTVAL 280 DEPARTMENT_ID DEPARTMENT_NAME LOCATION_ID 280 unknown 1700 290 TRAINING 2500 300 EDUCATION 2400 310 unknown 1200 7/5/12 7/5/12 75
    • PL/SQL DECLARE v_id NUMBER := 163; BEGIN raise_salary(v_id); -- invoke procedure COMMIT; END; 7/5/12 7/5/12 76
    • PL/SQL CREATE OR REPLACE PROCEDURE process_emps IS CURSOR emp_cursor IS SELECT employee_id FROM employees; BEGIN FOR emp_rec IN emp_cursor LOOP raise_salary(emp_rec.employee_id); -- invoke procedure END LOOP; COMMIT; END process_emps; / DROP PROCEDURE raise_sal; 7/5/12 7/5/12 77
    • PL/SQL CREATE OR REPLACE PROCEDURE leave_emp2 (p_id IN employees.employee_id%TYPE) IS PROCEDURE log_exec IS BEGIN INSERT INTO log_table (user_id, log_date) VALUES (user, sysdate); END log_exec; BEGIN DELETE FROM employees WHERE employee_id = p_id; log_exec; END leave_emp2; / 7/5/12 7/5/12 78
    • PL/SQL Called PROCEDURE p2 Called PROCEDURE p2 Procedure IS Procedure IS .. .. BEGIN BEGIN .. .. -- error -- error Calling .. Calling .. Procedure EXCEPTION Procedure EXCEPTION -- handled -- unhandled PROCEDURE p1 END p2; PROCEDURE p1 END p2; IS IS .. .. BEGIN BEGIN Control .. .. returns P2(arg1); Control P2(arg1); to the returns exception .. .. to the section EXCEPTION calling EXCEPTION of .. procedure .. calling END p1; END p1; procedure 7/5/12 7/5/12 79
    • PL/SQL Summary  Procedure – performs an action  IN OUT IN OUT  DEFAULT option  Passing Parameters  Invoking Procedure from Anonymous and another Procedure  Standalone Procedure  Handled / Un-Handled Exception  Removing Procedure 7/5/12 7/5/12 80
    • PL/SQL Creating Functions 7/5/12 7/5/12 81
    • PL/SQL  A function is a named PL/SQL Block that returns a Value.  A function can be stored in the database as a schema object for repeated execution.  A function is called as part of an expression. Function  The function must have IN parameter (default) at least one RETURN clause in the header. at least one RETURN statement in the executable. FUNCTION RETURN dataype  Accept only valid SQL data-types, not PL/SQL types IS | AS .. ..  Return only valid SQL data-types, not PL/SQL types BEGIN .. RETURN v_s .. EXCEPTION .. .. END; 7/5/12 7/5/12 82
    • PL/SQL CREATE OR REPLACE FUNCTION get_sal (p_id IN employees.employee_id%TYPE) RETURN NUMBER IS v_salary employees.salary%TYPE := 0; BEGIN SELECT salary INTO v_salary 117 p_id FROM employees WHERE employee_id = p_id; RETURN v_salary RETURN v_salary; END get_sal; / VARIABLE g_sal NUMBER EXECUTE :g_sal := get_sal(117) PRINT g_sal 7/5/12 7/5/12 83
    • PL/SQL CREATE OR REPLACE FUNCTION tax(p_value IN NUMBER) RETURN NUMBER IS BEGIN RETURN (p_value * 0.08); END tax; / SELECT employee_id, last_name, salary, tax(salary) FROM employees WHERE department_id = 60; SELECT employee_id, tax(salary) FROM employees WHERE tax(salary) > (SELECT MAX(tax(salary)) FROM employees WHERE department_id = 30) ORDER BY tax(salary) DESC; 7/5/12 7/5/12 84
    • PL/SQL CREATE OR REPLACE FUNCTION dml_call_sql (p_sal NUMBER) RETURN NUMBER IS BEGIN INSERT INTO employees(employee_id, last_name, email, hire_date, job_id, salary) VALUES (999, ‘employee1’, ’emp1@cpm.com’, sysdate, ‘SA_MAN’, 1000); RETURN (p_sal + 100); END; / UPDATE employees SET salary = dml_call_sql(2000) WHERE employee_id = 170; 7/5/12 7/5/12 85
    • PL/SQL EXECUTE privilege for subprograms hr.employees SELECT  In-Direct access GRANT SELECT EXECUTE scott.query_emp ON employees TO scott;  Direct access PROCEDURE query_emp GRANT EXECUTE Green Scott ON query_emp TO green; 7/5/12 7/5/12 86
    • PL/SQL Default AUTHID DEFINER 7/5/12 7/5/12 87
    • PL/SQL USER_OBJECTS Provides general information about the object USER_SOURCE Provides the text of the object USER_ERRORS Shows compilation errors SHOW ERRORS PROCEDURE log_execution DESCRIBE tax 7/5/12 7/5/12 88
    • PL/SQL Creating Packages 7/5/12 7/5/12 89
    • PL/SQL  Group logically related PL/SQL types, items and subprograms.  Allow the Oracle Server to read multiple objects into memory at once. Package Procedure A SPECIFICATION declaration Package Procedure B BODY definition Procedure A definition 7/5/12 7/5/12 90
    • PL/SQL Public Variable Package Procedure A SPECIFICATION Public Procedure declaration Private Variable Procedure B Package definition Private Procedure BODY Procedure A Public procedure definition Local Variable 7/5/12 7/5/12 91
    • PL/SQL  CREATE PACKAGE keyword for package specification. CREATE PACKAGE BODY keyword for package body.  A package specification can exist without a package body, but the package body cannot exist without a package specification. Package XYZ Package UVW 7/5/12 7/5/12 92
    • PL/SQL CREATE OR REPLACE PACKAGE comm_package IS g_comm NUMBER := 0.10; PROCEDURE reset_comm (p_comm IN NUMBER); END comm_package; CREATE OR REPLACE PACKAGE BODY comm_package IS FUNCTION validate_comm (p_comm IN NUMBER) RETURN BOOLEAN IS v_max_comm NUMBER; BEGIN SELECT MAX(commission_pct) INTO v_max_comm FROM employees; IF p_comm > v_max_comm THEN RETURN(FALSE); ELSE RETURN (TRUE); END IF; END validate_comm; Invoke a function within the PROCEDURE reset_comm (p_comm IN NUMBER) IS same package BEGIN IF validate_comm(p_comm)THEN g_comm := p_comm --reset the global variable ELSE RAISE_APPLICATION_ERROR(-20210,’Invalid Commission’); END IF; END reset_comm; END comm_package; 7/5/12 7/5/12 93
    • PL/SQL  Invoke a package procedure from SQL Worksheet EXECUTE comm_package.rest_comm(0.15)  Invoke a package procedure in a different schema EXECUTE scott.comm_package.rest_comm(0.15)  Invoke a package procedure in a remote database EXECUTE scott.comm_package.rest_comm@db1(0.15) 7/5/12 7/5/12 94
    • PL/SQL CREATE OR REPLACE PACKAGE global_consts IS mile_2_kilo CONSTANT NUMBER := 1.6093; kilo_2_mile CONSTANT NUMBER := 0.6214; yard_2_meter CONSTANT NUMBER := 0.9144; meter_2_yard CONSTANT NUMBER := 1.0936; END global_consts; / EXECUTE DBMS_OUTPUT.PUT_LINE(’20 miles = ‘ || 20 * global_consts.mile_2_kilo|| ‘ km’) CREATE OR REPLACE PROCEDURE me_to_yard ( p_meter IN NUMBER, p_yard OUT NUMBER) IS BEGIN p_yard := p_meter * global_consts.meter_2_yard; END me_to_yard; / VARIABLE yard NUMBER EXECUTE me_to_yard (1, :yard) PRINT yard 7/5/12 7/5/12 95
    • PL/SQL  Enables you to use the same name for different subprograms inside a PL/SQL block, a subprogram, or a package  Requires the formal parameters of the subprograms to differ in number, order, or data type family. CREATE OR REPLACE PACKAGE over_pack IS PROCEDURE add_dept (p_deptno IN departments.department_id%TYPE, p_name IN departments.department_name%TYPE DEFAULT ‘unknown’, p_loc IN departments.location_id%TYPE DEFAULT 0); PROCEDURE add_dept (p_dno IN dept.dno%TYPE DEFAULT 0, p_dname IN dept.dname%TYPE DEFAULT ‘unknown’); PROCEDURE add_dept (p_dname IN col_dept.dname%TYPE DEFAULT ‘unknown’, p_hod IN col_dept.hod%TYPE DEFAULT ‘unknown’); END over_pack; / 7/5/12 7/5/12 96
    • PL/SQL CREATE OR REPLACE PACKAGE BODY over_pack IS PROCEDURE add_dept (p_deptno IN departments.department_id%TYPE, p_name IN departments.department_name%TYPE DEFAULT ‘unknown’, p_loc IN departments.location_id%TYPE DEFAULT 0) IS BEGIN INSERT INTO departments(department_id, department_name, location_id) VALUES (p_deptno, p_name, p_loc); END add_dept; PROCEDURE add_dept (p_dno IN dept.dno%TYPE DEFAULT 0 , p_dname IN dept.dname%TYPE DEFAULT ‘unknown’) IS BEGIN INSERT INTO dept(dno, dname) VALUES (p_dno, p_dname); END add_dept; PROCEDURE add_dept (p_dname IN college_dept.dname%TYPE DEFAULT ‘unknown’, p_hod IN college_dept.hod%TYPE DEFAULT ‘unknown’) IS BEGIN INSERT INTO college_dept(dname, hod) VALUES (p_dname, p_hod); END add_dept; END over_pack; EXECUTE over_pack.add_dept(980 , ‘Education’, 2500) EXECUTE over_pack.add_dept(90 , ‘Training’) EXECUTE over_pack.add_dept(‘Database’, ‘DeCarl’) 7/5/12 7/5/12 97
    • PL/SQL CREATE OR REPLACE PACKAGE taxes_pack IS FUNCTION tax(p_value IN NUMBER) RETURN NUMBER; END taxes_pack; / CREATE OR REPLACE PACKAGE BODY taxes_pack IS FUNCTION tax(p_value IN NUMBER) RETURN NUMBER IS v_rate NUMBER := 0.08; BEGIN RETURN (p_value * v_rate); END tax; END taxes_pack; / SELECT last_name, salary, taxes_pack.tax(salary) FROM employees; 7/5/12 7/5/12 98
    • PL/SQL Better Performance The entire package is loaded into memory when the package is first referenced. There is only one copy in memory for all users. The dependency hierarchy is simplified. Over-loading : Multiple subprograms of the same name. DROP PACKAGE package_name; DROP PACKAGE BODY package_name; 7/5/12 7/5/12 99
    • PL/SQL Summary Package SPECIFICATION Package BODY Invoking Package – EXECUTE Bodiless Package Overloading User Defined Package 7/5/12 7/5/12 100
    • PL/SQL Oracle Supplied Packages 7/5/12 7/5/12 101
    • PL/SQL  Are provided with the Oracle server.  Extend the functionality of the database.  Parse Check for the statement syntax Ensure the referenced object exist Ensure the relevant privilege to those object.  Bind Join the fetched value to the variable / column / column alias  Execute All necessary information and resources are met  Fetch (only SELECT) Rows requested are selected and ordered. 7/5/12 7/5/12 102
    • PL/SQL  Use OPEN_CURSOR to establish an area memory to process a SQL statement.  Use PARSE to establish the validity of the SQL statement.  Use EXECUTE function to run the SQL statement. The function returns the number of row processed.  Use CLOSE_CURSOR to close the cursor. CREATE OR REPLACE PROCEDURE delete_all_rows (p_tab_name IN VARCHAR2, p_rows_del OUT NUMBER) IS cursor_name INTEGER; BEGIN cursor_name := DBMS_SQL.OPEN_CURSOR; DBMS_SQL.PARSE(cursor_name, ‘DELETE FROM ‘ || p_tab_name, DBMS_SQL.NATIVE); p_rows_del := DBMS_SQL.EXECUTE (cursor_name); DBMS_SQL.CLOSE_CURSOR(cursor_name); END; / VARIABLE deleted NUMBER EXECUTE delete_all_rows(‘employees’, :deleted) PRINT deleted 7/5/12 7/5/12 103
    • PL/SQL CREATE OR REPLACE PROCEDURE del_rows (p_table_name IN VARCHAR2, p_rows_deld OUT NUMBER) IS BEGIN EXECUTE IMMEDIATE ‘delete from ‘ || p_table_name; p_rows_deld := SQL%ROWCOUNT; END; / VARIABLE deleted NUMBER EXECUTE del_rows(‘test_employees’, :deleted) PRINT deleted 7/5/12 7/5/12 104
    • PL/SQL Summary Oracle Supplied Packages  Are provided with the Oracle server.  Extend the functionality of the database. 7/5/12 7/5/12 105
    • PL/SQL LOB - Large OBjects 7/5/12 7/5/12 106
    • PL/SQL  Used to store large unstructured data such as text, graphic, images, films and sound waveforms  Stores locator to the LOB’s value CLOB BLOB BFILE 7/5/12 7/5/12 107
    • PL/SQL ALTER TABLE employees ADD emp_video BFILE; CREATE OR REPLACE DIRECTORY log_files AS ‘c:pict’; GRANT READ ON DIRECTORY log_files TO PUBLIC; CREATE OR REPLACE PROCEDURE load_emp_bfile (p_file_loc IN VARCHAR2) IS v_file BFILE; v_filename VARCHAR2(16); CURSOR emp_cursor IS SELECT first_name FROM employees WHERE department_id = 60 FOR UPDATE; BEGIN FOR emp_record IN emp_cursor LOOP v_filename := emp_record.first_name || ‘.bmp’; v_file := BFILENAME(p_file_loc, v_filename); DBMS_LOB.FILEOPEN(v_file); UPDATE employees SET emp_video = v_file WHERE CURRENT OF emp_cursor; DBMS_OUTPUT.PUT_LINE(‘LOADED FILE: ‘||v_filename||‘Size:‘ || DBMS_LOB.GETLENGTH(v_file)); DBMS_LOB.FILECLOSE(v_file); END LOOP; END load_emp_bfile; EXECUTE load_emp_bfile(‘LOG_FILES’) 7/5/12 7/5/12 108
    • PL/SQL Database Triggers 7/5/12 7/5/12 109
    • PL/SQL  Is a PL/SQL block or a PL/SQL procedure associated with a table, view, schema, or the database.  Executes implicitly whenever a particular event takes place.  Two types of Triggers  Application Trigger Fires whenever an event occurs with a particular application.  Database Trigger Fires whenever a data event (such as DML) or system event (such as logon or shutdown on a schema or database) 7/5/12 7/5/12 110
    • PL/SQL  BEFORE Execute the trigger body before the triggering DML event on a table.  AFTER Execute the trigger body after the triggering DML event on a Table  INSTEAD OF Used for views. 7/5/12 7/5/12 111
    • PL/SQL  DML statement INSERT INTO departments (department_id,department_name, location_id) VALUES (400, ‘COUNSULTING’, 2400); BEFORE statement trigger Triggering BEFORE row trigger action AFTER row trigger AFTER statement trigger UPDATE employees SET salary = salary * 1.5 WHERE department_id = 30; BEFORE statement trigger 30 30 BEFORE row trigger Triggering 30 AFTER row trigger 30 ... ... action 30 BEFORE row trigger 30 AFTER row trigger AFTER statement trigger 7/5/12 7/5/12 112
    • PL/SQL  Create a trigger to restrict inserts into the EMPLOYEES table to certain business hours, i.e. 8.00 am to 6.00 pm, Monday through Friday. CREATE OR REPLACE TRIGGER secure_emp BEFORE INSERT ON employees BEGIN IF (TO_CHAR(SYSDATE,’DY’) IN (‘SAT’,’SUN’) OR TO_CHAR(SYSDATE,’HH24:MI’) NOT BETWEEN ’08:00’ AND ’18:00’) THEN RAISE_APPLICATION_ERROR(-20500,’You many insert into Employees table only during business hours.’); END IF; END secure_emp; 7/5/12 7/5/12 113
    • PL/SQL  Combine several triggering events into one trigger body. CREATE OR REPLACE TRIGGER secure_emp1 BEFORE INSERT OR UPDATE OR DELETE ON employees BEGIN IF (TO_CHAR(SYSDATE,’DY’) IN (‘SAT’,’SUN’) OR TO_CHAR(SYSDATE,’HH24:MI’) NOT BETWEEN ‘08:00’ AND ’18:00’) THEN IF DELETING THEN RAISE_APPLICATION_ERROR(-20502,’Delete during office hours...’); ELSIF INSERTING THEN RAISE_APPLICATION_ERROR(-20503,’Insert during office hours...’); ELSIF UPDATING(‘SALARY’) THEN RAISE_APPLICATION_ERROR(-20504,’Update SALARY during office hours’); ELSE RAISE_APPLICATION_ERROR(-20506,’Update during office hours’); END IF; END IF; END; 7/5/12 7/5/12 114
    • PL/SQL Data Operation : OLD Value : NEW Value INSERT NULL Inserted value UPDATE Value before update Value after update DELETE Value before delete NULL  Create a trigger to allow job id other than AD_PRES , VD_VP cannot earn more than 15000 CREATE OR REPLACE TRIGGER restrict_salary BEFORE INSERT OR UPDATE OF salary ON employees FOR EACH ROW BEGIN IF NOT (:NEW.job_id IN (‘AD_PRES’, ‘AD_VP’)) AND :NEW.salary > 15000 THEN RAISE_APPLICATION_ERROR(-20202,’Employees cannot earn more than this amount’); END IF; END; / 7/5/12 7/5/12 115
    • PL/SQL  Only Available for ROW Triggers CREATE OR REPLACE TRIGGER audit_emp_values AFTER DELETE OR INSERT OR UPDATE ON employees FOR EACH ROW BEGIN INSERT INTO aud_emp(user_name, timestampid, old_lname, new_lname, old_title, new_title, old_salary, new_salary) VALUES (USER, SYSDATE, :OLD.employee_id, :OLD.last_name, :NEW.last_name, :OLD.job_id, :NEW.job_id, :OLD.salary, :NEW.salary); END; / SELECT * FROM aud_emp; 7/5/12 7/5/12 116
    • PL/SQL  To restrict the trigger action for those rows satisfy a certain condition, provide WHEN clause. CREATE OR REPLACE TRIGGER derive_commpct BEFORE INSERT OR UPDATE OF salary ON employees FOR EACH ROW WHEN (NEW.job_id = ‘SA_REP’) BEGIN IF INSERTING THEN :NEW.commission_pct := 0; ELSIF :OLD.commission_pct IS NULL THEN :NEW.commission_pct := 0; ELSE :NEW.commission_pct := OLD.commission_pct + 0.05; END IF; END; / 7/5/12 7/5/12 117
    • PL/SQL TRIGGERS PROCEDURES Source Code USER_TRIGGERS Source Code USER_SOURCE Implicitly Invoked Explicitly Invoked COMMIT, SAVEPOINT, ROLLBACK COMMIT, SAVEPOINT, are not allowed ROLLBACK are allowed ALTER TRIGGER trigger_name DISABLE|ENABLE; ALTER TABLE table_name DISABLE|ENABLE ALL TRIGGERS; DROP TRIGGER trigger_name; 7/5/12 7/5/12 118
    • PL/SQL  CREATE, ALTER or DROP  Logging ON / OFF  Shutting down or starting up the database. CREATE OR REPLACE TRIGGER logon_trig AFTER LOGON ON SCHEMA | DATABASE BEGIN INSERT INTO log_trig_table(user_id, log_date, action) VALUES (USER, SYSDATE, ‘Logging on’); END logon_trig; / CREATE OR REPLACE TRIGGER logoff_trig BEFORE LOGOFF ON SCHEMA | DATABASE BEGIN INSERT INTO log_trig_table(user_id, log_date, action) VALUES (USER, SYSDATE, ‘Logging Off’); END logoff_trig; / 7/5/12 7/5/12 119
    • PL/SQL CREATE OR REPLACE TRIGGER check_salary BEFORE UPDATE OF salary ON EMPLOYEES FOR EACH ROW WHEN (NEW.salary < OLD.salary) BEGIN RAISE_APPLICATION_ERROR(-20509, ‘Do not decrease salary..’); END check_salary; / CREATE OR REPLACE TRIGGER log_emp BEFORE INSERT ON EMPLOYEES CALL log_execution; END log_emp; / 7/5/12 7/5/12 120
    • PL/SQL Summary  Application Trigger  Database Trigger  Row Trigger :OLD :NEW  Restrict Row Trigger - WHEN  Calling a Procedure - CALL proc_name 7/5/12 7/5/12 121
    • PL/SQL Managing Dependencies 7/5/12 7/5/12 122
    • PL/SQL Procedure View or Table Procedure Direct Direct dependency dependency Referenced Dependent Indirect Dependent dependency Referenced 7/5/12 7/5/12 123
    • PL/SQL utldtree.sql Direct Local Dependency Procedure Procedure View Table Procedure Procedure View Table Definition changed INVALID INVALID INVALID SELECT name, type, referenced_name, referenced_type FROM user_dependencies WHERE referenced_name IN (‘EMPLOYEES’,’EMP_VW’); EXECUTE deptree_fill(‘TABLE’,’HR’,’EMPLOYEES’); ideptree SELECT nested_level, type, name FROM deptree Indirect ORDER BY seq#; dependency 7/5/12 7/5/12 124
    • PL/SQL ALTER PROCEDURE proc_name COMPILE; ALTER FUNCTION func_name COMPILE; ALTER PACKAGE pack_name COMPILE [PACKAGE]; ALTER PACKAGE pack_name COMPILE BODY; ALTER TRIGGER trig_name COMPILE; 7/5/12 7/5/12 125