一。查询A表的所有字段，还要查询和A表关联的B表的C字段的个数，条件是A.Fnum=B.Cnum

在上例中，学习人数和完成人数之前的字段都是A表的字段，学习人数和完成人数需要关联查询B表。

?

select FCOURSEWARE_NAME,fid ,fcourseware_type ,ftime_long ,flanguages ,fowner ,fcontributor ,fon_line_time,stu.sc,s.c,fstate

from COURSEWARE c left join (select count(1) as sc,course_number from user_course_study_info where course_number is not null group by course_number ) stu 

on stu.course_number = c.fcourse_id left join (select count(1) as c,course_number from user_course_study_info where BROWSE_SCORE=100 and course_number is not null group by course_number) s

on s.course_number = c.fcourse_id

?

二。 查A的记录时，同时要查询出和A关联的C表总记录数，C表不直接和A表关联，C表和B表是多对一，B和A是多对一。

select t.fid, t.fcourse_code,t.fcourse_name, t.funit,t.flevel, tcou.tc, tstu.lcc, ware.cs
 from course_info t left join (select count(1) as tc,fcourse_id from teachplan_course where fcourse_id is not null group by fcourse_id)
 tcou on tcou.fcourse_id=t.fid left join (select fid, fcourse_id from Teach_Arrangement where fcourse_id is not null group by fcourse_id,fid)
 tarr on tarr.fcourse_id=t.fid left join (select count(1) lcc,FTEACH_ARRANGEMENT_ID from TEACHPLAN_STUDENT_CHOOSE where FTEACH_ARRANGEMENT_ID is not null group by FTEACH_ARRANGEMENT_ID)
  tstu on tstu.FTEACH_ARRANGEMENT_ID=tarr.fid left join (select count(1) as cs,FCOURSE_ID from courseware where FCOURSE_ID is not null group by FCOURSE_ID)
  ware on ware.FCOURSE_ID=t.fid where 1=1

?

?

?