Decode

Encyclopedia : D : DE : DEC : Decode

DECODE is a single-row function in Oracle which applies conditional logic to SQL queries. This function works very much like an IF-THEN-ELSE statement.

Syntax:

DECODE (expression1,
value1, return_value1,
value2, return_value2, ...
valueN, return_valueN,
[default_return_value])

How it works

If expression1 equals value1 then return_value1 is returned by DECODE function, and if expression1 equals value2 then return_value2 is returned and so on…..

The optional default_return_value is returned if expression1 does not match with any of value1,value2,…..valueN values.

In short

IF expression1 = valueN   THEN return_valueN  ELSE default_return_value

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