sql子查询中的问题
select A.CLASSNAME,A.ENROLDATE,A.GRADUATEDATE,A.SPECIALITYNAME,B.DEPNAME,a.RATINGSUM,c.num,f.num2 from
XJ_CLASSES a ,FW_DEPARTMENT b,(select classid, count(classid)as num from xj_student group by classid) c,fw_codelist d,
(select classid, count(classid)as num2 from xj_student group by classid)f WHERE
a.TRAINLEVEL=D.CODEVALUE
and D.CODELABEL='士官职业技术教育'
and c.classid(+)=a.classid
and A.SPECIALITYNAME='电气自动化'
and A.DEPID=b.DEPID(+)
and A.ENROLDATE like '%16%'
and f.classid(+)=A.CLASSID;
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以上sql中:and c.classid(+)=a.classid 和 and A.ENROLDATE like '%16%'
and f.classid(+)=A.CLASSID; 这些写法能不能讲解下,‘%16%’是什么意思