IF

Data Manipulation (DML) StatementsBuilt-in Scalar Functions

`IF` Examples

An example using the IF statement.Assume that the variables FIRST, LINE2 and LAST were declared earlier.
```
...
IF (FIRST IS NOT NULL) THEN
  LINE2 = FIRST || ' ' || LAST;
ELSE
  LINE2 = LAST;
...
```
Given IF … THEN … ELSE is a statement, it is possible to chain them together.Assume that the INT_VALUE and STRING_VALUE variables were declared earlier.
```
IF (INT_VALUE = 1) THEN
  STRING_VALUE = 'one';
ELSE IF (INT_VALUE = 2) THEN
  STRING_VALUE = 'two';
ELSE IF (INT_VALUE = 3) THEN
  STRING_VALUE = 'three';
ELSE
  STRING_VALUE = 'too much';
```
This specific example can be replaced with a simple CASE or the DECODE function.

`WHILE … DO`

Looping construct

Syntax

[label:]
WHILE (<condition>) DO
  <compound_statement>

Table 1. `WHILE … DO` Parameters
Argument	Description
label	Optional label for `LEAVE` and `CONTINUE`.Follows the rules for identifiers.
condition	A logical condition returning `TRUE`, `FALSE` or `UNKNOWN`
compound_statement	A single statement, or statements wrapped in `BEGIN … END`

A WHILE statement implements the looping construct in PSQL.The statement or the block of statements will be executed as long as the condition returns TRUE.Loops can be nested to any depth.

IF

IF Examples

WHILE …​ DO

`IF` Examples

`WHILE … DO`