Importance of PL/SQL-Structure of PL/SQL Block-Different Data Types and Programming Construction. Section of Pl/SQL Block

1. Programming Language for SQL
COMBINE DATABASE LANGUAGE AND PROCEDURAL PROGRAMMING LANGUAGE

2. Introduction
 PL/SQL Purpose
 PL/SQL Block
 PL/SQL Data Types
 Programming Construction in PL/SQL
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3. PL/SQL Block
 PL/SQL Block has three parts
 Declaration
 Execution
 Exception
 Structure of PL/SQL Block
Declare
Variables;
Begin
Statements;
Exception
Statements;
End;
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4. PL/SQL Data Types
 Same Data Types which SQL supports like char, varchar2, number, long,
raw, lobs etc
 Composite Data Types
 %type
 If the declaration variable width is not suitable width then we can get an error called
numeric or value error. To over come this we can declare the variable type as
%type.
 For example to declare one variable as job attribute type of employee table we can use as
j1 employee.job%type
 %rowtype
 To retrieve the information from the table which is having more number of attributes
instead of declaring more number of variable we can declare only one variable as
%rowtype. For example let us take employee table having 7 attributes instead of
declaring 7 variables we can declare only one variable as employee%rowtype
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5. Programming constructions
 Programming constructions represent how the program is going to be
executed. There are three programming constructions
 Sequence
 Without any conditions if statements are executed that is called Sequence.
 Selection
 Based on the condition if the execution control is changed from one place to another
place. For this purpose we can use conditional statements if, select case
 Syntax (IF-THEN) Syntax(IF-THEN-ELSE)
IF condition THEN IF condition THEN
Statements; Statements;
END IF; ELSE
Statements;
END IF;
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IF condition THEN {...statements to execute when condition is TRUE...} END IF;

6. Programming Constructions
 Syntax (IF-THEN-ELSIF-THEN-ELSE) Syntax (Case-Selector)
IF condition THEN Case Expression
Statements; when value then statement
ELSIF condition THEN when value then statement
Statements; else
ELSE End Case
Statements;
END IF
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7. Programming Constructions
 Iteration or Repetition
 Executing some set of statements number of time is called Iteration or Repetition.
For this purpose we can use loops.
 Syntax For .. Loop
For variable in Starting number . . Ending number Loop
Statements;
End Loop;
 Syntax While .. Loop
While condition Loop
Statements;
End Loop;
 Syntax for Repeat .. Until Loop (same as Do . . While)
Loop
Statements;
EXIT when condition;
End Loop;
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