複雜的左連線查詢

一。查詢a表的所有字段，還要查詢和a表關聯的b表的c欄位的個數，條件是a.fnum=b.cnum

在上例中，學習人數和完**數之前的字段都是a表的字段，學習人數和完**數需要關聯查詢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

select * from (select t.fid,

t.fcourse_code,
t.fcourse_name,
t.funit,
t.flevel,
t.fcreatetime,
sum(arr.tc) as tc,
sum(choose.tc2) as tc2
from course_info t left join (select count(1) as tc,
fid,
fcourse_id
from teach_arrangement
group by fid, fcourse_id) arr on arr.fcourse_id = t.fid left join (select count(1) as tc2,
fteach_arrangement_id
from teachplan_student_choose
group by fteach_arrangement_id) choose on choose.fteach_arrangement_id = arr.fid
group by t.fid,
t.fcourse_code,
t.fcourse_name,
t.funit,
t.flevel,
t.fcreatetime) temp left join (select count(1) as tc3,
fcourse_id
from courseware
group by fcourse_id) ware on ware.fcourse_id = temp.fid

複雜的左連線查詢

一。查詢a表的所有字段，還要查詢和a表關聯的b表的c欄位的個數，條件是a.fnum b.cnum 在上例中，學習人數和完 數之前的字段都是a表的字段，學習人數和完 數需要關聯查詢b表。select fcourseware name,fid fcourseware type ftime long fl...

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