tsql - 如果@@rowcount>0 将@@rowcount 重置为0，则执行。为什么？

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@@Rowcount is used to inform the number of rows affected for the last select,insert,update or delete statements

declare @row int select 100 if @@rowcount>0  set @row=@@rowcount ...

The above will return 0 because as soon as if @@rowcount>0 is executed it is reset to 0 as it doesn't return any rows. So always assign to variable first

为什么声明 if @@rowcount>0重置 @@rowcount到 0？不是 @@rowcount的值吗？仅受选择、插入、更新和删除语句的影响？

谢谢

Answer 1

它受最后一条语句的影响。像这个 SET 语句

Declare @row int
select 100 union all select 200 union all select 300
set @row = @@rowcount;
SELECT @row, @@rowcount

如果您阅读了 actual Microsoft SQL Server Docs on MSDN ，它举例说明了哪些语句会影响 @@ROWCOUNT .例如，“例如”意味着其他语句如 IF 也会将其设置为零

Statements such as USE, SET <option>, DEALLOCATE CURSOR, CLOSE CURSOR, BEGIN TRANSACTION or COMMIT TRANSACTION reset the ROWCOUNT value to 0.