If-else keywords
IF (condition)
Statement or statement block
ELSE
Statement or statement block
Statement or statement block with begin ... End indicates
IF (condition)
BEGIN
Statement 1
Statement 2
END
For example:
DECLARE @test INT
SET @test =1
SELECT @test =avg (score) from Stu WHERE stu.name= ' Lilu '
IF (@test =1)
PRINT @test
ELSE
BEGIN
IF exists (SELECT score from Stu WHERE stu.name= ' AA ')
BEGIN
DELETE from Stu WHERE stu.name= ' AA ' and score=99
END
INSERT into Stu VALUES (' AA ', 99)
SELECT score from Stu
WHERE name= ' AA '
END
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Case keyword
Case
Case
When condition 1 then result 1
When condition 2 then result 2
END
For example:
CREATE TABLE SS
(
Name varchar (10),
Score Float
)
INSERT into SS values (' Small white ', 99)
INSERT into SS values (' Little black ', 77)
INSERT into SS values (' Xiao Li ', 58)
SELECT name,
Score=case
When score<60 then ' E '
When score between, and then ' D '
When score between and "C"
When score between and the then ' B '
ElSE ' A '
END
from SS
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While keyword
while (condition)
Statement or statement block
[Breake]
DECLARE @test INT
SET @test =2
while (@test <20)
BEGIN
SET @[email protected]+2
IF (@test <>7)
BEGIN
PRINT @test
IF (@test =18)
Break
END
ELSE
IF (@test =7)
CONTINUE
END
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This article is from the "Linux_woniu" blog, make sure to keep this source http://llu1314.blog.51cto.com/5925801/1965331
SQL Process Control Statements