MySQL查询帮助请加入多个表

Question

我有这4张桌子 （见图）

我想做的是这个

UID | f_name | m_name | l_name |后缀|班级|受试者

000 | jan | s | gerry | null | test |艺

001 | rey | s | ronald | null | test2 | 123

但是我创建的这个查询给了我这个输出

SELECT CONCAT(tbl_users.f_name, ' ', tbl_users.m_name, ' ', tbl_users.l_name, ' ', tbl_users.suffix) AS insName, tbl_classinstructor.UID, tbl_subject.subject, tbl_class.class FROM tbl_class, tbl_classinstructor LEFT OUTER JOIN tbl_users ON tbl_users.UID = tbl_classinstructor.UID, tbl_classsubject LEFT OUTER JOIN tbl_subject ON tbl_classsubject.SID = tbl_subject.SID

UID | f_name | m_name | l_name |后缀|班级|受试者

000 | jan | s | gerry | null | test |艺

000 | jan | s | gerry | null | test | 123

001 | rey | s | ronald | null | test2 | arts

001 | rey | s | ronald | null | test2 | 123

提前致谢

Answer 1

正确使用left join。它应该如何

SELECT 
CONCAT(tbl_users.f_name, ' ', tbl_users.m_name, ' ', tbl_users.l_name, ' ', tbl_users.suffix) AS insName, 
tbl_classinstructor.UID, 
tbl_subject.subject, 
tbl_class.class FROM tbl_class
LEFT OUTER JOIN tbl_classinstructor on tbl_classinstructor.CID = tbl_class.CID
LEFT OUTER JOIN tbl_users ON tbl_users.UID = tbl_classinstructor.UID
LEFT OUTER JOIN tbl_classsubject on tbl_classsubject.CID = tbl_class.CID
LEFT OUTER JOIN tbl_subject ON tbl_classsubject.SID = tbl_subject.SID