Apache Hive : HPL/SQL - CASE Expression

CASE expression allows you to implement IF-THEN-ELSE logic in expressions.

Syntax:

Simple CASE expression:

CASE expr
  WHEN expr THEN expr
  ...
  [ELSE expr] 
END

Searched CASE expression:

CASE 
  WHEN boolean_expr THEN expr
  ...
  [ELSE expr] 
END

Notes:

• NULL is returned if none of the WHEN expressions is matched and ELSE clause is not specified

Examples:

Simple CASE expression:

 CASE state
   WHEN 'AZ' THEN 'Arizona'
   WHEN 'CA' THEN 'California'
   ELSE 'N/A'
 END 

Searched CASE expression:

 CASE 
   WHEN state = 'AZ' THEN 'Arizona'
   WHEN state = 'CA' THEN 'California'
   ELSE 'N/A'
 END 

Compatibility: Oracle, IBM DB2, SQL Server, Teradata, MySQL, PostgreSQL and Netezza.

See also:

• DECODE Function