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关于 or and or 加括号的触发问题

Derekwong 2019-05-10 10:51:59

where (a=1 or a=2) and (c=1 or c=2 or c=3)



--请问是不是以下条件都触发



a=1 and c=1

a=1 and c=2

a=1 and c=3



a=2 and c=1

a=2 and c=2

a=2 and c=3

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吉普赛的歌 2019-05-12

简单的问题，验证一下其实更快

USE tempdb
GO
IF OBJECT_ID('t') IS NOT NULL DROP TABLE t
GO
CREATE TABLE t(
	a INT,
	c INT
)
GO
SET NOCOUNT ON
INSERT INTO t VALUES (1,1)
INSERT INTO t VALUES (1,2)
INSERT INTO t VALUES (1,3)
INSERT INTO t VALUES (2,1)
INSERT INTO t VALUES (2,2)
INSERT INTO t VALUES (2,3)
INSERT INTO t VALUES (3,1)
INSERT INTO t VALUES (3,2)
INSERT INTO t VALUES (3,3)
INSERT INTO t VALUES (4,1)
INSERT INTO t VALUES (4,2)
INSERT INTO t VALUES (4,3)

SELECT * FROM t WHERE (a=1 or a=2) and (c=1 or c=2 or c=3)
/*
a           c
----------- -----------
1           1
1           2
1           3
2           1
2           2
2           3
*/

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