Question

Since @A is never declared, sql server should throw an error, but it doesn’t. Why is that?

DECLARE @i int = 1;
IF @i > 10
BEGIN
  DECLARE @A int = 100;
END

PRINT @A; // doesn't return any result

thanx

Answer 1

SQL Server does not have block level variable scoping.

It’s per batch/stored proc etc

From MSDN (my bold)

The scope of a variable is the range
of Transact-SQL statements that can
reference the variable. The scope of a
variable lasts from the point it is
declared until the end of the batch or
stored procedure in which it is
declared.