PL/SQL Decode

The Decode function compares one expression to one or more other expressions and, when the search term is found, returns the match result expression.

Decode syntax

DECODE (expression , search, result [, search , result]... [, default])

Decode example

STUDENT_ID	FIRST_NAME	LAST_NAME	CITY
1	Daniel	SCOTT	New York
2	Anthony	SIMMONS	Chicago
3	Sophia	THOMPSON	Los Angeles

SELECT s.STUDENT_ID, s.FIRST_NAME, s.LAST_NAME, s.CITY,
DECODE(s.CITY, 'Los Angeles', 'L.A.', 'New York', 'N.Y.', s.CITY) AS SHORT_CITY
FROM students s;

STUDENT_ID	FIRST_NAME	LAST_NAME	CITY	SHORT_CITY
1	Daniel	SCOTT	New York	N.Y.
2	Anthony	SIMMONS	Chicago	Chicago
3	Sophia	THOMPSON	Los Angeles	L.A.

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