SQL Server Conditional Flow

Question

If I write two SELECT statements in a IF EXISTS condition with a AND clause in between these select queries, does both queries get executed even if the first SELECT returns false?

IF EXISTS (SELECT....) AND EXISTS(SELECT ....)
BEGIN

END

Does the SQL Server Engine execute both the SQL Statement in this scenario?

Thanks Krish

Answer 1

You can prevent the second scan by doing this:

declare @test bit
select @test = case when exists(select 1...) then 1 else 0 end
if @test = 1
begin
    --1st test passed
    select @test = case when exists(select 2...) then 1 else 0 end
end
if @test = 1
begin
    print 'both exists passed'
end