Oracle OCP 考试系列培训                 之          1Z0-007 Lesson3                          www.OracleOnLinux.cn3-1   Copyright ...
3         Using Single-Row Functions to               Customize Output3-2   Copyright © 2011,   www.OracleOnLinux . All ri...
Objectives      After completing this lesson, you should be able to do      the following:       • Describe various types ...
SQL Functions       Input                                                Output                                     Functi...
Two Types of SQL Functions                                     Functions         Single-row                               ...
Single-Row Functions      Single-row functions:       • Manipulate data items       • Accept arguments and return one valu...
Single-Row Functions                                   Character                                  Single-row      General ...
Character Functions                                    Character                                    functions      Case-ma...
Case-Manipulation Functions      These functions convert case for character strings:       Function                       ...
Using Case-Manipulation Functions       Display the employee number, name, and department       number for employee Higgin...
Character-Manipulation Functions       These functions manipulate character strings:       Function                       ...
Using the Character-Manipulation                        Functions                                                         ...
Number Functions       •   ROUND: Rounds value to specified decimal       •   TRUNC: Truncates value to specified decimal ...
Using the ROUND Function                         1                         2       SELECT ROUND(45.923,2), ROUND(45.923,0)...
Using the TRUNC Function                         1                         2       SELECT TRUNC(45.923,2), TRUNC(45.923), ...
Using the MOD Function       For all employees with job title of Sales Representative,       calculate the remainder of th...
Working with Dates       •   The Oracle database stores dates in an internal numeric           format: century, year, mont...
Working with Dates       SYSDATE is a function that returns:       •   Date       •   Time3-18        Copyright © 2011,   ...
Arithmetic with Dates       •   Add or subtract a number to or from a date for a           resultant date value.       •  ...
Using Arithmetic Operators                           with Dates       SELECT last_name, (SYSDATE-hire_date)/7 AS WEEKS    ...
Date Functions       Function                         Result       MONTHS_BETWEEN                   Number of months betwe...
Using Date Functions       Function                                                Result       MONTHS_BETWEEN            ...
Using Date Functions       Assume SYSDATE = 25-JUL-03:       Function                                       Result       R...
Practice 3: Overview of Part 1       This practice covers the following topics:        • Writing a query that displays the...
Conversion Functions                                    Data type                                   conversion           I...
Implicit Data Type Conversion       For assignments, the Oracle server can automatically       convert the following:     ...
Implicit Data Type Conversion       For expression evaluation, the Oracle Server can       automatically convert the follo...
Explicit Data Type Conversion                   TO_NUMBER                     TO_DATE       NUMBER                     CHA...
Explicit Data Type Conversion                   TO_NUMBER                     TO_DATE       NUMBER                     CHA...
Using the TO_CHAR Function with Dates       TO_CHAR(date, format_model)       The format model:        • Must be enclosed ...
Elements of the Date Format Model       Element                          Result       YYYY                             Ful...
Elements of the Date Format Model       •   Time elements format the time portion of the date:            HH24:MI:SS AM   ...
Using the TO_CHAR Function with Dates       SELECT last_name,              TO_CHAR(hire_date, fmDD Month YYYY)            ...
Using the TO_CHAR Function with Numbers       TO_CHAR(number, format_model)       These are some of the format elements th...
Using the TO_CHAR Function with Numbers       SELECT   TO_CHAR(salary, $99,999.00) SALARY       FROM     employees       W...
Using the TO_NUMBER and TO_DATE                       Functions       •   Convert a character string to a number format   ...
Using the TO_NUMBER and TO_DATE                       Functions       •   Convert a character string to a number format   ...
RR Date Format       Current Year              Specified Date       RR Format      YY Format       1995                   ...
Example of RR Date Format       To find employees hired prior to 1990, use the RR date       format, which produces the sa...
Nesting Functions       •   Single-row functions can be nested to any level.       •   Nested functions are evaluated from...
Nesting Functions       SELECT last_name,         UPPER(CONCAT(SUBSTR (LAST_NAME, 1, 8), _US))       FROM   employees     ...
General Functions       The following functions work with any data type and       pertain to using nulls:        • NVL (ex...
NVL Function       Converts a null value to an actual value:        • Data types that can be used are date, character,    ...
Using the NVL Function       SELECT last_name, salary, NVL(commission_pct, 0),     1          (salary *12) + (salary *12*N...
Using the NVL2 Function       SELECT last_name, salary, commission_pct,        1              NVL2(commission_pct,        ...
Using the NULLIF Function                                                           1       SELECT first_name, LENGTH(firs...
Using the COALESCE Function       •   The advantage of the COALESCE function over the           NVL function is that the C...
Using the COALESCE Function       SELECT last_name,              COALESCE(manager_id,commission_pct, -1) comm       FROM  ...
Conditional Expressions       •   Provide the use of IF-THEN-ELSE logic within a           SQL statement       •   Use two...
CASE Expression       Facilitates conditional inquiries by doing the work of       an IF-THEN-ELSE statement:       CASE e...
Using the CASE Expression       Facilitates conditional inquiries by doing the work of       an IF-THEN-ELSE statement:   ...
Using the CASE Expression       Facilitates conditional inquiries by doing the work of       an IF-THEN-ELSE statement:   ...
DECODE Function       Facilitates conditional inquiries by doing the work of a       CASE expression or an IF-THEN-ELSE st...
Using the DECODE Function       SELECT last_name, job_id, salary,              DECODE(job_id, IT_PROG,                 1.1...
Using the DECODE Function       Display the applicable tax rate for each employee in       department 80:       SELECT las...
Summary       In this lesson, you should have learned how to:        • Perform calculations on data using functions       ...
Practice 3: Overview of Part 2       This practice covers the following topics:        • Creating queries that require the...
Practice 3       Q1: Which two are character manipulation functions?       (Choose two.)       A.   TRIM       B.   REPLAC...
Practice 3       Q2:The CUSTOMERS table has these columns:       Q2:The       CUSTOMER_ID     NUMBER(4)      NOT NULL     ...
Practice 3       Q2:       A promotional sale is being advertised to the       customers in France. Which WHERE clause    ...
Practice 3       Q3: Which SELECT statement will get the result       elloworld from the string HelloWorld?       A. SELEC...
Practice 3       Q4:Evaluate the SQL statement:       Q4:Evaluate       SELECT LPAD(salary,10,*) FROM EMP               LP...
Practice 3       Q5:Evaluate the SQL statement:       Q5:Evaluate       SELECT ROUND(TRUNC(MOD(1600,10),-1),2)       FROM ...
Practice 3       Q6:Which SELECT statement should you use to       Q6:Which       extract the year from the system date an...
Practice 3       Q7:Which three SELECT statements display 2000 in       Q7:Which       the format "$2,000.00"?       A. SE...
Practice 3       Q8:Which SQL statement displays the date March 19,       Q8:Which       2001 in a format that appears as ...
Practice 3       C. SELECT TO_CHAR(TO_DATE(19-Mar-2001, DD-       Mon-YYYY), fmDdspth "of" Month YYYY HH:MI:SS       AM) N...
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Lesson03 学会使用单行函数

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Oracle OCP考试之007第3章,学会使用单行函数

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Lesson03 学会使用单行函数

  1. 1. Oracle OCP 考试系列培训 之 1Z0-007 Lesson3 www.OracleOnLinux.cn3-1 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  2. 2. 3 Using Single-Row Functions to Customize Output3-2 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  3. 3. Objectives After completing this lesson, you should be able to do the following: • Describe various types of functions that are available in SQL • Use character, number, and date functions in SELECT statements • Describe the use of conversion functions3-3 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  4. 4. SQL Functions Input Output Function arg 1 Function performs action arg 2 Result value arg n3-4 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  5. 5. Two Types of SQL Functions Functions Single-row Multiple-row functions functions Return one result Return one result per row per set of rows3-5 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  6. 6. Single-Row Functions Single-row functions: • Manipulate data items • Accept arguments and return one value • Act on each row that is returned • Return one result per row • May modify the data type(隐式转换数据类型) type( • Can be nested(可以嵌套,多层嵌套) nested( • Accept arguments that can be a column or an expression function_name [(arg1, arg2,...)]3-6 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  7. 7. Single-Row Functions Character Single-row General Number functions Conversion Date3-7 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  8. 8. Character Functions Character functions Case-manipulation Character-manipulation functions functions LOWER CONCAT UPPER SUBSTR INITCAP LENGTH INSTR LPAD | RPAD TRIM REPLACE3-8 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  9. 9. Case-Manipulation Functions These functions convert case for character strings: Function Result LOWER(SQL Course) LOWER( Course sql course UPPER(SQL Course) UPPER( Course SQL COURSE INITCAP(SQL Course) INITCAP( Course Sql Course3-9 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  10. 10. Using Case-Manipulation Functions Display the employee number, name, and department number for employee Higgins: SELECT employee_id, last_name, department_id FROM employees WHERE last_name = higgins; no rows selected SELECT employee_id, last_name, department_id FROM employees WHERE LOWER(last_name) = higgins;3-10 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  11. 11. Character-Manipulation Functions These functions manipulate character strings: Function Result CONCAT(Hello, World) HelloWorld SUBSTR(HelloWorld,1,5) SUBSTR(HelloWorld Hello LENGTH(HelloWorld) 10 INSTR(HelloWorld, W) 6 LPAD(salary,10,*) LPAD(salary,10, *****24000 RPAD(salary, 10, *) * 24000***** 24000* REPLACE BLACK and BLUE (JACK and JUE,J,BL) TRIM(H FROM HelloWorld) elloWorld3-11 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  12. 12. Using the Character-Manipulation Functions 1 SELECT employee_id, CONCAT(first_name, last_name) NAME, job_id, LENGTH (last_name), 2 INSTR(last_name, a) "Contains a?" FROM employees 3 WHERE SUBSTR(job_id, 4) = REP; 1 2 33-12 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  13. 13. Number Functions • ROUND: Rounds value to specified decimal • TRUNC: Truncates value to specified decimal • MOD: Returns remainder of division Function Result ROUND(45.926, 2) 45.93 TRUNC(45.926, 2) 45.92 MOD(1600, 300) 1003-13 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  14. 14. Using the ROUND Function 1 2 SELECT ROUND(45.923,2), ROUND(45.923,0), ROUND(45.923,-1) 3 FROM DUAL; 1 2 3 DUAL is a dummy table that you can use to view results from functions and calculations.3-14 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  15. 15. Using the TRUNC Function 1 2 SELECT TRUNC(45.923,2), TRUNC(45.923), TRUNC(45.923,-1) 3 FROM DUAL; 1 2 33-15 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  16. 16. Using the MOD Function For all employees with job title of Sales Representative, calculate the remainder of the salary after it is divided by 5,000. SELECT last_name, salary, MOD(salary, 5000) FROM employees WHERE job_id = SA_REP;3-16 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  17. 17. Working with Dates • The Oracle database stores dates in an internal numeric format: century, year, month, day, hours, minutes, and seconds. • The default date display format is DD-MON-RR. – Enables you to store 21st-century dates in the 20th century by specifying only the last two digits of the year – Enables you to store 20th-century dates in the 21st century in the same way SELECT last_name, hire_date FROM employees WHERE hire_date < 01-FEB-88;3-17 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  18. 18. Working with Dates SYSDATE is a function that returns: • Date • Time3-18 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  19. 19. Arithmetic with Dates • Add or subtract a number to or from a date for a resultant date value. • Subtract two dates to find the number of days between those dates. • Add hours to a date by dividing the number of hours by 24.3-19 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  20. 20. Using Arithmetic Operators with Dates SELECT last_name, (SYSDATE-hire_date)/7 AS WEEKS FROM employees WHERE department_id = 90;3-20 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  21. 21. Date Functions Function Result MONTHS_BETWEEN Number of months between two dates ADD_MONTHS Add calendar months to date NEXT_DAY Next day of the date specified LAST_DAY Last day of the month ROUND Round date TRUNC Truncate date3-21 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  22. 22. Using Date Functions Function Result MONTHS_BETWEEN 19.6774194 (01-SEP-95,11-JAN-94) ADD_MONTHS (11-JAN-94,6) 11-JUL-94 NEXT_DAY (01-SEP-95,FRIDAY) 08-SEP-95 LAST_DAY (01-FEB-95) 28-FEB-953-22 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  23. 23. Using Date Functions Assume SYSDATE = 25-JUL-03: Function Result ROUND(SYSDATE,MONTH) 01-AUG-03 ROUND(SYSDATE ,YEAR) 01-JAN-04 TRUNC(SYSDATE ,MONTH) 01-JUL-03 TRUNC(SYSDATE ,YEAR) 01-JAN-033-23 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  24. 24. Practice 3: Overview of Part 1 This practice covers the following topics: • Writing a query that displays the current date • Creating queries that require the use of numeric, character, and date functions • Performing calculations of years and months of service for an employee3-24 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  25. 25. Conversion Functions Data type conversion Implicit data type Explicit data type conversion conversion3-25 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  26. 26. Implicit Data Type Conversion For assignments, the Oracle server can automatically convert the following: From To VARCHAR2 or CHAR NUMBER VARCHAR2 or CHAR DATE NUMBER VARCHAR2 DATE VARCHAR23-26 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  27. 27. Implicit Data Type Conversion For expression evaluation, the Oracle Server can automatically convert the following: From To VARCHAR2 or CHAR NUMBER VARCHAR2 or CHAR DATE SELECT last_name, salary FROM employees WHERE salary>100003-27 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  28. 28. Explicit Data Type Conversion TO_NUMBER TO_DATE NUMBER CHARACTER DATE TO_CHAR TO_CHAR3-28 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  29. 29. Explicit Data Type Conversion TO_NUMBER TO_DATE NUMBER CHARACTER DATE TO_CHAR TO_CHAR3-29 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  30. 30. Using the TO_CHAR Function with Dates TO_CHAR(date, format_model) The format model: • Must be enclosed by single quotation marks • Is case-sensitive • Can include any valid date format element • Has an fm element to remove padded blanks or suppress leading zeros • Is separated from the date value by a comma3-30 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  31. 31. Elements of the Date Format Model Element Result YYYY Full year in numbers YEAR Year spelled out (in English) MM Two-digit value for month MONTH Full name of the month MON Three-letter abbreviation of the month DY Three-letter abbreviation of the day of the week DAY Full name of the day of the week DD Numeric day of the month3-31 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  32. 32. Elements of the Date Format Model • Time elements format the time portion of the date: HH24:MI:SS AM 15:45:32 PM • Add character strings by enclosing them in double quotation marks: DD "of" MONTH 12 of OCTOBER • Number suffixes spell out numbers: ddspth fourteenth3-32 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  33. 33. Using the TO_CHAR Function with Dates SELECT last_name, TO_CHAR(hire_date, fmDD Month YYYY) AS HIREDATE FROM employees; …3-33 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  34. 34. Using the TO_CHAR Function with Numbers TO_CHAR(number, format_model) These are some of the format elements that you can use with the TO_CHAR function to display a number value as a character: Element Result 9 Represents a number 0 Forces a zero to be displayed $ Places a floating dollar sign L Uses the floating local currency symbol . Prints a decimal point , Prints a comma as thousands indicator3-34 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  35. 35. Using the TO_CHAR Function with Numbers SELECT TO_CHAR(salary, $99,999.00) SALARY FROM employees WHERE last_name = Ernst;3-35 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  36. 36. Using the TO_NUMBER and TO_DATE Functions • Convert a character string to a number format using the TO_NUMBER function: TO_NUMBER(char[, format_model]) • Convert a character string to a date format using the TO_DATE function: TO_DATE(char[, format_model]) • These functions have an fx modifier. This modifier specifies the exact matching for the character argument and date format model of a TO_DATE function.3-36 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  37. 37. Using the TO_NUMBER and TO_DATE Functions • Convert a character string to a number format using the TO_NUMBER function: TO_NUMBER(char[, format_model]) • Convert a character string to a date format using the TO_DATE function: TO_DATE(char[, format_model]) • These functions have an fx modifier. This modifier specifies the exact matching for the character argument and date format model of a TO_DATE function3-37 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  38. 38. RR Date Format Current Year Specified Date RR Format YY Format 1995 27-OCT-95 1995 1995 1995 27-OCT-17 2017 1917 2001 27-OCT-17 2017 2017 2001 27-OCT-95 1995 2095 If the specified two-digit year is: 0–49 50–99 50– If two digits The return date is in The return date is in of the 0–49 the current century the century before current the current one year are: The return date is in The return date is in 50–99 the century after 50– the current century the current one3-38 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  39. 39. Example of RR Date Format To find employees hired prior to 1990, use the RR date format, which produces the same results whether the command is run in 1999 or now: SELECT last_name, TO_CHAR(hire_date, DD-Mon-YYYY) FROM employees WHERE hire_date < TO_DATE(01-Jan-90,DD-Mon-RR);3-39 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  40. 40. Nesting Functions • Single-row functions can be nested to any level. • Nested functions are evaluated from deepest level to the least deep level. F3(F2(F1(col,arg1) ,arg2),arg3) F3(F2 F1(col,arg1),arg2),arg3) F2( Step 1 = Result 1 Step 2 = Result 2 Step 3 = Result 33-40 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  41. 41. Nesting Functions SELECT last_name, UPPER(CONCAT(SUBSTR (LAST_NAME, 1, 8), _US)) FROM employees WHERE department_id = 60; SELECT last_name, NVL(TO_CHAR(manager_id), No Manager) NVL(TO_CHAR TO_CHAR(manager_id), FROM employees WHERE manager_id IS NULL;3-41 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  42. 42. General Functions The following functions work with any data type and pertain to using nulls: • NVL (expr1, expr2) • NVL2 (expr1, expr2, expr3) • NULLIF (expr1, expr2) • COALESCE (expr1, expr2, ..., exprn)3-42 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  43. 43. NVL Function Converts a null value to an actual value: • Data types that can be used are date, character, and number. • Data types must match: match: – NVL(commission_pct,0) – NVL(hire_date,01-JAN-97) – NVL(job_id,No Job Yet) SELECT last_name, NVL(TO_CHAR(manager_id), No Manager) NVL(TO_CHAR TO_CHAR(manager_id), FROM employees WHERE manager_id IS NULL;3-43 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  44. 44. Using the NVL Function SELECT last_name, salary, NVL(commission_pct, 0), 1 (salary *12) + (salary *12*NVL(commission_pct, 0)) AN_SAL (salary* 12* FROM employees; 2 … 1 23-44 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  45. 45. Using the NVL2 Function SELECT last_name, salary, commission_pct, 1 NVL2(commission_pct, SAL+COMM, SAL) income 2 FROM employees WHERE department_id IN (50, 80); 1 23-45 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  46. 46. Using the NULLIF Function 1 SELECT first_name, LENGTH(first_name) "expr1", last_name, LENGTH(last_name) "expr2", 2 FROM NULLIF(LENGTH(first_name), LENGTH(last_name)) result employees; 3 … 1 2 33-46 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  47. 47. Using the COALESCE Function • The advantage of the COALESCE function over the NVL function is that the COALESCE function can take multiple alternate values. • If the first expression is not null, the COALESCE function returns that expression; otherwise, it does a COALESCE of the remaining expressions.3-47 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  48. 48. Using the COALESCE Function SELECT last_name, COALESCE(manager_id,commission_pct, -1) comm FROM employees ORDER BY commission_pct; …3-48 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  49. 49. Conditional Expressions • Provide the use of IF-THEN-ELSE logic within a SQL statement • Use two methods: – CASE expression – DECODE function3-49 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  50. 50. CASE Expression Facilitates conditional inquiries by doing the work of an IF-THEN-ELSE statement: CASE expr WHEN comparison_expr1 THEN return_expr1 [WHEN comparison_expr2 THEN return_expr2 WHEN comparison_exprn THEN return_exprn ELSE else_expr] END3-50 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  51. 51. Using the CASE Expression Facilitates conditional inquiries by doing the work of an IF-THEN-ELSE statement: SELECT last_name, job_id, salary, CASE job_id WHEN IT_PROG THEN 1.10 salary * WHEN ST_CLERK THEN 1.15 salary * WHEN SA_REP THEN 1.20 salary * ELSE salary END "REVISED_SALARY" FROM employees; … …3-51 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  52. 52. Using the CASE Expression Facilitates conditional inquiries by doing the work of an IF-THEN-ELSE statement: SELECT last_name, job_id, salary,hire_date, CASE WHEN months_between(sysdate,hire_date)/12>=20 THEN 2.00*salary 2.00* WHEN job_id in (ST_CLERK,SA_REP) (ST_CLERK SA_REP) ST_CLERK, THEN 1.15*salary 1.15* WHEN salary<=5000 THEN 1.20*salary 1.20* ELSE salary END "REVISED_SALARY" FROM employees;3-52 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  53. 53. DECODE Function Facilitates conditional inquiries by doing the work of a CASE expression or an IF-THEN-ELSE statement: DECODE(col|expression, search1, result1 [, search2, result2,...,] [, default])3-53 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  54. 54. Using the DECODE Function SELECT last_name, job_id, salary, DECODE(job_id, IT_PROG, 1.10 salary, * ST_CLERK, 1.15 salary, * SA_REP, 1.20 salary, * salary) REVISED_SALARY FROM employees; … …3-54 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  55. 55. Using the DECODE Function Display the applicable tax rate for each employee in department 80: SELECT last_name, salary, DECODE (TRUNC(salary/2000, 0), 0, 0.00, 1, 0.09, 2, 0.20, 3, 0.30, 4, 0.40, 5, 0.42, 6, 0.44, 0.45) TAX_RATE FROM employees WHERE department_id = 80;3-55 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  56. 56. Summary In this lesson, you should have learned how to: • Perform calculations on data using functions • Modify individual data items using functions • Manipulate output for groups of rows using functions • Alter date formats for display using functions • Convert column data types using functions • Use NVL functions • Use IF-THEN-ELSE logic3-56 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  57. 57. Practice 3: Overview of Part 2 This practice covers the following topics: • Creating queries that require the use of numeric, character, and date functions • Using concatenation with functions • Writing case-insensitive queries to test the usefulness of character functions • Performing calculations of years and months of service for an employee • Determining the review date for an employee3-57 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  58. 58. Practice 3 Q1: Which two are character manipulation functions? (Choose two.) A. TRIM B. REPLACE C. TRUNC D. TO_DATE E. MOD F. CASE3-58 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  59. 59. Practice 3 Q2:The CUSTOMERS table has these columns: Q2:The CUSTOMER_ID NUMBER(4) NOT NULL CUSTOMER_NAME VARCHAR2(100) NOT NULL STREET_ADDRESS VARCHAR2(150) CITY_ADDRESS VARCHAR2(50) STATE_ADDRESS VARCHAR2(50) PROVINCE_ADDRESS VARCHAR2(50) COUNTRY_ADDRESS VARCHAR2(50) POSTAL_CODE VARCHAR2(12) CUSTOMER_PHONE VARCHAR2(20)3-59 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  60. 60. Practice 3 Q2: A promotional sale is being advertised to the customers in France. Which WHERE clause identifies customers that are located in France? A. WHERE lower(country_address) = "france" B. WHERE lower(country_address) = france C. WHERE lower(country_address) IS france D. WHERE lower(country_address) = %france% E. WHERE lower(country_address) LIKE %france%3-60 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  61. 61. Practice 3 Q3: Which SELECT statement will get the result elloworld from the string HelloWorld? A. SELECT SUBSTR( HelloWorld,1) FROM dual; B. SELECT INITCAP(TRIM (HelloWorld, 1,1)) FROM dual; C. SELECT LOWER(SUBSTR(HelloWorld, 1, 1) FROM dual; D. SELECT LOWER(SUBSTR(HelloWorld, 2, 1) FROM dual; E. SELECT LOWER(TRIM (H FROM HelloWorld)) FROM dual;3-61 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  62. 62. Practice 3 Q4:Evaluate the SQL statement: Q4:Evaluate SELECT LPAD(salary,10,*) FROM EMP LPAD(salary,10,* WHERE EMP_ID = 1001; If the employee with the EMP_ID 1001 has a salary of 17000, what is displayed? A. 17000.00 B. 17000***** 17000* C. ****170.00 D. **17000.00 E. an error statement3-62 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  63. 63. Practice 3 Q5:Evaluate the SQL statement: Q5:Evaluate SELECT ROUND(TRUNC(MOD(1600,10),-1),2) FROM dual; What will be displayed? A. 0 B. 1 C. 0.00 D. an error statement3-63 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  64. 64. Practice 3 Q6:Which SELECT statement should you use to Q6:Which extract the year from the system date and display it in the format "1998"? A. SELECT TO_CHAR(SYSDATE,yyyy) FROM dual; B. SELECT TO_DATE(SYSDATE,yyyy) FROM dual; C. SELECT DECODE(SUBSTR(SYSDATE, 8), YYYY) FROM dual; D. SELECT DECODE(SUBSTR(SYSDATE, 8), year) FROM dual; E. SELECT TO_CHAR(SUBSTR(SYSDATE, 8,2),yyyy) FROM dual;3-64 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  65. 65. Practice 3 Q7:Which three SELECT statements display 2000 in Q7:Which the format "$2,000.00"? A. SELECT TO_CHAR(2000, $#,###.##) FROM dual; B. SELECT TO_CHAR(2000, $0,000.00) FROM dual; C. SELECT TO_CHAR(2000, $9,999.00) FROM dual; D. SELECT TO_CHAR(2000, $9,999.99) FROM dual; E. SELECT TO_CHAR(2000, $2,000.00) FROM dual; F. SELECT TO_CHAR(2000, $N,NNN.NN) FROM dual;3-65 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  66. 66. Practice 3 Q8:Which SQL statement displays the date March 19, Q8:Which 2001 in a format that appears as "Nineteenth of March 2001 12:00:00 AM"? A. SELECT TO_CHAR(TO_DATE(19-Mar-2001, DD- Mon-YYYY), fmDdspth "of" Month YYYY fmHH:MI:SS AM) NEW_DATE FROM dual; B. SELECT TO_CHAR(TO_DATE(19-Mar-2001, DD- Mon-YYYY), Ddspth "of" Month YYYY fmHH:MI:SS AM) NEW_DATE FROM dual;3-66 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn
  67. 67. Practice 3 C. SELECT TO_CHAR(TO_DATE(19-Mar-2001, DD- Mon-YYYY), fmDdspth "of" Month YYYY HH:MI:SS AM) NEW_DATE FROM dual; D. SELECT TO_CHAR(TO_DATE(19-Mar-2001, DD- Mon-YYYY), fmtDdspth "of" Month YYYY fmtHH:MI:SS AM) NEW_DATE FROM dual; fmtHH:MI:SS3-67 Copyright © 2011, www.OracleOnLinux . All rights reserved. OracleOnLinux OracleOnLinux.cn

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