Control structures syntax; IF THEN ELSE, CASE, WHILE .
IF THEN ELSE
The IF THEN ELSE syntax in TSQL is kinda weird if you ask me … I forget them ‘all the time’, created examples below for my reference.
IF THEN
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if 1 = 1
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begin
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print 'true'
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end
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go
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IF THEN – short notation
IF THEN ELSE
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if 1 = 1
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begin
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print 'true'
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end
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else
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begin
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print 'false'
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end
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go
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IF THEN ELSE – short notation
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if 1 = 1
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print 'true'
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else
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print 'false'
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go
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Multiple IF THEN ELSE blocks
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if 1 = 1
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begin
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print '1 = 1'
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end
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else
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if 1 = 2
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begin
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print '1 = 2'
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end
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else
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if 1 = 3
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begin
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print '1 = 3'
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end
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go
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CASE
TSQL has the CASE control structure …
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declare @i int, @r int
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set @i = 1
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set @r =
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case @i
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when 1 then 1
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when 2 then 2
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else 0
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end
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print @r
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go
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WHILE
Eternal loop
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while 1 = 1
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print 'true'
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go
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Simple WHILE loop
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declare @i int
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set @i = 0
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while @i < 10
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begin
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print @i
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set @i = @i + 1
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end
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go
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Beautifully concise!
The best page on the internet for T-SQL control structures!
Thank you.