sql - 为什么即使条件计算结果为 false，也会创建在 IF 语句内声明的变量？

Question

由于@A从未被声明过，sql server应该抛出一个错误，但它没有。这是为什么？

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

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

谢谢

Answer 1

SQL Server 没有 block 级变量作用域。

它是按批处理/存储过程等

From MSDN (我的粗体)

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.