请问各位高手:下面这条语句运行不成功,如果换成on a.user_id=b.user_id就成功,但是不是我想要的结果
select a.document_types,count(b.document_types) from gss_documen_cate a left join gss_documentation b on a.document_types=b.document_types where a.user_id=18 group by a.document_types;
select a.document_types,count(b.document_types) from gss_documen_cate a left join gss_documentation b on a.document_types=b.document_types where a.user_id=18 group by a.document_types;
from gss_documen_cate a left join (select document_types from gss_documentation where user_id=18) b
on a.document_types=b.document_typesselect document_types,(select count(*) from gss_documentation where user_id=18)
from gss_documen_cate