ORA-01427: single-row subquery returns more than one row

问题

my query is as follows:

SELECT DISTINCT * 
FROM (SELECT depts."ID", depts.arabic_description 
      FROM sng_v_org_unit_departments depts 
      INNER JOIN (SELECT "ID", arabic_description, ouh_id   
                  FROM sng_v_org_unit_headers 
                  START WITH "ID" = 
                  (SELECT headid 
                   FROM emppirmesion per 
                   inner join  empldabdetail empinfo 
                           on per.emprecid = empinfo.recid 
                   where lower(empinfo.shortname) =  lower('ibmadmin') and 
                         per.headid > 0 and 
                         per.clasisymbolicname = 'SoHiring') 
                  CONNECT BY PRIOR "ID" = ouh_id) heads 
      ON depts.ouh_id = heads."ID"
      UNION 
      SELECT per.depid, depts.arabic_description 
      FROM emppirmesion per 
      inner join empldabdetail empinfo on per.emprecid = empinfo.recid 
      inner join sng_v_org_unit_departments depts on per.depid = depts."ID" 
      where lower(empinfo.shortname) = lower('ibmadmin') and 
            per.depid > 0 and 
            per.clasisymbolicname = 'SoHiring')

I am getting an exception ORA-01427: single-row subquery returns more than one row if i have more than one row in the emppirmesion that have the same clasisymbolicname although they have differnet headid values and this exception shouldn't occur in this case, please advise about that.

回答1:

Issue was the START WITH expects single value and my subquery was returning multiple values, so i changed the query from:

START WITH "ID" = 
                  (SELECT headid 
                   FROM emppirmesion per 
                   inner join  empldabdetail empinfo 
                           on per.emprecid = empinfo.recid 
                   where lower(empinfo.shortname) =  lower('ibmadmin') and 
                         per.headid > 0 and 
                         per.clasisymbolicname = 'SoHiring')

to:

Where "ID" in 
                  (SELECT headid 
                   FROM emppirmesion per 
                   inner join  empldabdetail empinfo 
                           on per.emprecid = empinfo.recid 
                   where lower(empinfo.shortname) =  lower('ibmadmin') and 
                         per.headid > 0 and 
                     per.clasisymbolicname = 'SoHiring') 

and it works fine.

来源：https://stackoverflow.com/questions/17521985/ora-01427-single-row-subquery-returns-more-than-one-row