Term: IF

Definition:
The Oracle IF keyword is part of the PL/SQL IF...THEN construct which implements conditional control in PL/SQL. Conditional Control refers to taking an alternative action instead of regular one, based on defined conditions or logic-based decisions. It allows conditional execution of statements in defined sequence. The IF...THEN construct is available in three formats:

IF...THEN
IF...THEN...ELSE
IF...THEN...ELSIF...ENDIF

IF THEN...END IF statement is a single-level conditional statement which executes a sequence of statements based on a given condition:

IF condition THEN

   executable statements 

END IF;

A plain-English example of this could be, "IF the temperature is below 50 degrees, THEN turn on the heater."

The IF-THEN-ELSE statement is next level of extension of above the IF-THEN statement, as it provides the ability to give direction for FALSE or NULL also.

IF condition THEN

   executable statements 1

ELSE

   executable statements 2 

END IF;

A plain-English example of this could be, "IF the temperature is below 50 degrees, THEN turn on the heater, ELSE open a window."

For multiple possible outcomes of a condition, we use the IF THEN ELSIF ENDIF statement.

IF condition1 THEN

   sequence_of_statements1

ELSIF condition2 THEN

   sequence_of_statements2

ELSE

   sequence_of_statements3

END IF;

Example Usage:

The block of code below looks at the value of the variable 'V_GRADE'. If it is 'P' then it prints out 'PASS'.

DECLARE

V_GRADE VARCHAR2(1) := 'P';

BEGIN

   IF V_GRADE = 'P' THEN

	DBMS_OUTPUT.PUT_LINE('PASS');

   END IF;

END;

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