用子查询更新，左联接

Question

i am building an UPDATE query that is subject to a WHERE clause contained in a subquery.

this query works when I restrict it to something like this :

WHERE id=
( 
   SELECT 
      u.id
    FROM USER u
    WHERE
   u.live = 1 
)

however my query requires a further subquery within the subsquery. below is an example of my query ;

UPDATE newsletters     
 SET personalHtml =2
   WHERE id=
    (
      SELECT  
         u.id,
         (SELECT 
            COUNT(lo.userId)
          FROM    
            list_members_login lo
                WHERE 
                    u.id = lo.userId
                ) as totalLogins

                FROM
                    user u  
                WHERE
                    u.live = 1 
                 AND   
                    u.jobId IN (2,4) 
                GROUP BY 
                     u.id    
                    HAVING 
                        totalLogins >= 4 
               ) 

i am getting the following error message:

Operand should contain 1 column(s)

Answer 1

1. The error means, it's expecting 1 value but subquery returning multiple results (say 1=(1,2,4) which is wrong). To resolve it you can use IN operand instead of = in where clause (say 1 IN (1,2,4)).
   
2. The subquery select should not contain multiple columns u.id and totalLogins in select clause.
   

Try below code. Hope this works.

UPDATE newsletters     
SET personalHtml =2
WHERE id IN
(
  SELECT  
         u.id
  FROM
          user u  
  WHERE
          u.live = 1 
  AND   
          u.jobId IN (2,4) 
  GROUP BY 
           u.id    
  HAVING 

            (SELECT 
                  COUNT(lo.userId)
                  FROM    
                  list_members_login lo
                  WHERE 
                  u.id = lo.userId
            ) >= 4 
   )

Answer 2

In your subquery you have 2 columns hence the error, remove totalLogins from subquery.

Also be noted that if your subquery returns more than 1 value it will again give you error stating subquery returna more than 1 value.Consider using in instead of =