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|类学科
000 | jan | s | gerry | |测试|艺术
001 | rey | s | ronald | null | test2 | 123
但是创建的这个查询我给了我这个输出
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|类学科
000 | jan | s | gerry | |测试|艺术
000 | jan | s | gerry | |测试| 123
001 | rey | s | ronald | null | test2 | arts
001 | rey | s | ronald | null | test2 | 123
提前致谢
最佳答案
正确使用left join。这里应该如何
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
关于mysql - MySQL查询帮助请连接多个表，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/28796136/