IF statement not raising error as expected-CodePudding

Assume @Ref <> 0 in first condition. Therefore my code will not reach the declaration of @XYZ (line 2).

I think it must raise an error in the second IF because of @XZY was not declared.

But I'm surprised that there is no error raised.

IF @Ref = 0 
BEGIN
    DECLARE @XYZ int

    SELECT @XYZ = RISKGROUP
    FROM POLCONT WITH (NOLOCK, NOWAIT) 
    WHERE CONT = 555
END

IF @RISKGROUP <> @XYZ  
BEGIN
    -- do something ...
END

For example.

In python it raises this error:

Error: local variable 'XYZ' referenced before assignment

CodePudding user response：

You need to declare your variable with a type before you can use it

declare @xyz int -- assuming the datatype of column riskgroup is also int

select @xyz = riskgroup
from   polcont
where  polcont = 555

EDIT

You altered your question since I have posted my answer, now your problem is you declare the variable in the wrong scope.

DECLARE @XYZ int

if @Ref = 0 
begin 
   SELECT @XYZ = RISKGROUP
   FROM   POLCONT --WITH (NOLOCK, NOWAIT) don't do nolock everywhere !
   WHERE  CONT = 555
end

if @RISKGROUP <> @XYZ  
begin
   -- do something ...
end

EDIT 2

As to your question why it does not give any error, that is strange indeed

See this DBFiddle I would indeed expect an error, but it somehow does not

This is explained in the documents as normal per design, though in my mind it is a flaw.
Also see this Question about the same subject

EDIT 3

So it seems that is does not matter much in TSQL where you declare your variables, but as a programmer I find this looking weird, so I prefer to put my variables in what is for me the correct scope.