SQL Server 2014显示的错误

Question

set @return=(SELECT u_id,u_pass from m_User where u_id = @userName AND u_pass=@userPass);

显示这样的错误

"Only one expression can be specified in the select list when the subquery is not introduced with EXISTS."

Answer 1

您不能在子查询中选择多个列。 在这里，您选择两列u_id,u_pass 。

根据需要仅选择一个。

如果@return是数据类型（例如varchar，int）

set @return=(SELECT u_id from m_User where u_id = @userName AND u_pass=@userPass);

要么

set @return=(SELECT u_pass from m_User where u_id = @userName AND u_pass=@userPass);