PostgreSQL SQL SELECT CASE WHEN

发布时间：2020-12-13 17:12:02 所属栏目：百科来源：网络整理

导读：The SQL CASE expression is a generic conditional expression,similar to if/else statements in other programming languages: CASE WHEN condition THEN result [ WHEN ... ] [ ELSE result ]END An example: SELECT * FROM test; a--- 1 2 3SELECT a,CA

TheSQLCASEexpression is a generic conditional expression,similar to if/else statements in other programming languages:

CASE WHEN condition THEN result
     [WHEN ...]
     [ELSE result]
END

An example:

SELECT * FROM test;

 a
---
 1
 2
 3


SELECT a,CASE WHEN a=1 THEN 'one'
            WHEN a=2 THEN 'two'
            ELSE 'other'
       END
    FROM test;

 a | case
---+-------
 1 | one
 2 | two
 3 | other

http://www.postgresql.org/docs/current/static/functions-conditional.html

（编辑：李大同）

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