SQL SERVER UPDATE的赋值次序

1) 先变量再字段

SET NOCOUNT ON;

DECLARE @i INT, @j INT

DECLARE @Table TABLE

(

Id1 INT,

Id2 INT

);

INSERT @Table(Id1, Id2)

SELECT 1, 10

UNION ALL

SELECT 2, 20

UNION ALL

SELECT 3, 30;

SELECT @i = 1, @j = 0

UPDATE @Table SET Id1 = @i, Id2 = Id1, @i = @i + 1

SELECT * FROM @Table

SELECT @i = 1, @j = 0

UPDATE @Table SET Id1 = @i, Id2 = @j, @j = @i + 10, @i = @i + 1

SELECT * FROM @Table

SET NOCOUNT OFF;

结果:

Id1 Id2

----------- -----------

2 1

3 2

4 3

Id1 Id2

----------- -----------

2 11

3 12

4 13

2) 变量之间, 从左到右

SET NOCOUNT ON;

DECLARE @i INT, @j INT

DECLARE @Table TABLE

(

Id1 INT,

Id2 INT

);

INSERT @Table(Id1, Id2)