[ACCEPTED]-How to check if a variable is already declared (T-SQL)?-tsql
The declaration of variables in tsql 4 does not follow the code path and use scope 3 like perhaps other languages does.
This code 2 shows that
@xx exists but is unassigned even 1 though the declaration was never executed.
if 1 = 0 begin declare @xx int = 10 end else begin declare @yy int = 20 end print coalesce(@xx, -100) print coalesce(@yy, -200)
IF you try to access a variable that has 4 not yet been defined, the T-SQL Script will 3 give you an error telling you the variable 2 isn't defined.
Msg 137, Level 15, State 2, Line 1 5 Must declare the scalar variable "@x".
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