pl / sql · faisal anwer & mohammad nadeem 1 . disadvantages of sql sql does not have any...
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PL / SQL
Faisal Anwer & Mohammad Nadeem
1
DISADVANTAGES OF SQL
SQL does not have any procedural capabilities:
Condition checking
Looping and branching
There is no provision for exception handling.
To overcome these problems and provide some additional
benefits, PL/SQL was developed.
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PL/SQL
PL/SQL is a programming language that supports SQL
data manipulation. But also provides:
facilities of conditional checking, looping and
branching.
provides exception handing facility.
supports variables to handle intermediate results.
and much more.
It is a superset of SQL.
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PL/SQL GENERIC BLOCK
PL/SQL blocks contain three sections
Declare section
Executable section
Exception-handling section
The executable section is the only mandatory section of the
block.
Both, the declaration and exception-handling sections are
optional.
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PL/SQL GENERIC BLOCK
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VARIOUS SECTIONS
Declare Section:
Variables and objects can be declared and initialized (if required) in
this section.
Once declared, they can be used in SQL statements.
Begin Section:
It consists of a set of SQL and PL/SQL statements.
Data manipulation, retrieval, looping and branching constructs are
specified in this section.
Exception Section:
Handles the errors that arise during execution on PL/SQL
statements.
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EXAMPLE
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INPUT / OUTPUT IN PL/SQL
Input:
n1 := &n1; (for command line inputting)
n1 := :n1; (for GUI inputting)
Output:
dbms_output.put_line(‘Your message');
dbms_output.put_line(‘ ‘) displays a message string.
If the Output is OFF and it can be made ON by:
SET SERVEROUTPUT ON;
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EXAMPLE
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EXAMPLE
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BASIC DATA TYPES
Number(p,s)
Char(n)
Varchar2(n)
Date
Boolean
%Type:
Declares a variable to have the same data type as that
of a previously defined variable or of a column in a
table.
Ex- Cname Client_Master.Name%Type;
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LOGICAL COMPARISONS
>
<
=
<=
>=
<>
Logical operators:
AND
OR
NOT
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CONDITIONAL STATEMENT
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EXAMPLE F
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LOOPING
Loop:
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EXAMPLE
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LOOPING
While loop:
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EXAMPLE
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LOOPING
For loop:
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EXAMPLE
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WHAT WE SAW TODAY
Generic PL/SQL Block
Various sections of a PL/SQL Block
Input/Output
Logical operators
Conditional Statement
Looping
Loop
While loop
For loop
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EXAMPLE
Write a PL/SQL code block that will accept an account no
from user and deduct 100 Rs from it if its balance it less
than some minimum balance.
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Write a PL/SQL code block that will accept an account no from user and
deduct 100 Rs from it if its balance it less than some minimum balance.
EXERCISE
Enter a number. If the number is 1 then print ‘One’. If the
number is 2 then print ‘Two’. Else print ‘’Neither One nor
Two’.
Enter an year. Find out whether it is a leap year or not.
Print 10 odd numbers starting from 1.
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