如何使用mysql EXISTS返回布尔值

Question

我想获得一个mysql查询的布尔输出.

我发出如下的查询

EXISTS (
    select 1 
    from someothertable 
    where someaccid = (
       select someid 
       from smtable 
       where username = 'someuser' 
       and password = 'somepassword')
)

这会1064在mysqlshell中返回一个错误并返回一个bool false php mysqli.

如何使用EXISTS命令获得输出为bool ？

提前致谢.

Answer 1

用途SELECT:

SELECT EXISTS (select 1 
               from someothertable 
               where someaccid = (select someid 
                                  from smtable 
                                  where username = 'someuser' and 
                                        password = 'somepassword'))

1如果EXISTS成功则返回,0否则返回.