CBSE Class 12 Informatics Practices Getting Started With Pl SQL Notes

CBSE Class 12 Informatics Practices Getting Started With pl sql study notes. Learning the important concepts is very important for every student to get better marks in examinations. The concepts should be clear which will help in faster learning. The attached concepts made as per NCERT and CBSE pattern will help the student to understand the chapter and score better marks in the exaages.minations.

GETTING STARTED WITH PL/SQL

SQL Vs PL/SQL:

Limitations of SQL are:
• No procedural capabilities .
• Time Consuming Processing or Network traffic.
• No Error Handling Routines/Procedures.

Advantages of PL/SQL are:

•Procedural Capabilities.

• Reduced Network Traffic.
• Error Handling Procedures/Routines.
• Facilitates Sharing.
• Improved Transaction Performance.
• Portable Code.

ANCHORED DECLARTION:
It refers to a declaration where a variable is declared with another variable or a table column used as its anchor.
PL/SQL use %TYPE declaration attribute for anchoring.

Ex: num1      NUMBER(5);
num2             num1%TYPE;
empsal          Emp.Salary%TYPE;

Note: Anchored types are evaluated at compile time.Thus,you need to recompile the change of
underlying type in the anchored variable.

TYPES OF PL/SQL VARIABLES:
• Local Variables.
• Substitution Variables.
• Bind or Host Variables.

PL/SQL BLOCK STRUCTURES:

DECLARE
/* definitions of

BEGIN

[EXCEPTION]

END;

TYPES OF BLOCKS:
• Anonymous Blocks: Blocks without headers.
• Named Blocks: Blocks having headers or labels like procedure,functions,packages or triggers.

PL/SQL CONTROL STRUCTURES:
• Sequence
• Selection
• Iteration.

SELECTION CONSTRUCT: (Condition Testing or Decision Making Statements)

1. Simple IF:-

Syntax:
       IF THEN
       Statement
       END IF;

Example:
DECLARE
a number;
BEGIN
a :=&a;
if a>100 THEN
dbms_output.put_line(a);
END IF;

2. IF…THEN…ELSE…END IF:-

Syntax:
       IF THEN
       Statement1;
       ELSE
       Statement2;
       END IF;
Example:

DECLARE
a number;
b number;
BEGIN
a :=&a;
b :=&b;
if a>b THEN
dbms_output.put_line(a);
ELSE
dbms_output.put_line(b);
END IF;

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