MySQL Database Error: Operand should contain 1 column(s)

Question

Here is the statement. The purpose isn't really important, just that I need to be able to tell what type of object the publication rule belongs to. Thanks!

select case(select count(mediaitemguid) from mediaitempublicationrules where publicationruleguid = '<snip>')
       when 0 then case(select count(catalogguid) from catalogpublicationrules where publicationruleguid = '<snip>')
           when 0 then case(select count(domainguid) from domaindefaultpublicationrules where publicationruleguid = '<snip>')
              when 0 then null
             else (select 'Domain', domainguid from domaindefaultpublicationrules where publicationruleguid = '<snip>')
             end
           else (select 'Catalog', catalogguid from catalogpublicationrules where publicationruleguid = '<snip>')
           end
       else (select 'MediaItem', mediaitemguid from mediaitempublicationrules where publicationruleguid = '<snip>')
       end;

EDIT: a little more clarification...this worked just fine until I put those 'Domain' 'Catalog' 'MediaItem' entries into the nested selects on the else statements. It's probably something fairly simple, just haven't run into that error before

Answer 1

The error indicate you should return single column instead of two

One way to fix is to use concat_ws like

select concat_ws(':', 'Domain', domainguid') ... <-- ':' is the delimiter