Oracle Multi-Table Association update

Drop table Course;create table course (ID integer,teacherno integer,teacherdesc varchar2 (+), TeacherName varchar2 (50), Coursename varchar2); INSERT into course values (1,100, ' Mr.zhang ', ' Zhangsan ', ' 中文版 '); INSERT into course values ( 2,101, ' Mr.wang ', ' Wangwu ', ' history '), insert into course values (2,101, ' Mr.wang ', ' Wangwu ', ' Chinese '); update course set Teacherdesc= ' Good Teacher ' where Teacherno=101;commit;drop table Teacher;create table Teacher (ID integer,teacherdesc VARCHAR2, TeacherName varchar2 (), insert into teacher values ("Mr.zhang", "Zhangsan"); insert into teacher VALUES (101, ' Mr.wang ', ' Wangwu '); update teacher set teacherdesc= ' excellent teacher ' where id=101;commit;select C.teacherdesc, C.teachername, T.teacherdesc, t.teachername from course C, teacher t where C.teacherno = T.id and (C.tea Cherdesc! = T.TEACHERDESC or C.teachername! = t.teachername); update course C Set (C.teacherdesc, C.teachername) =       (Select T.teacherdesc, T.teachernameFrom teacher T whereC.teacherno = T.id and (c.teacherdesc! = T.TEACHERDESC or C.teachername! = t.teachername)) Where exists (select 1 from teacher T whereC.teacherno = T.id and (c.teacherdesc! = T.TEACHERDESC or C.teachername! = t.teachername)); Commit;select C.teacherdesc, C.teachername, T.teacherdesc, t.teachername from course C, teacher t where C.teacherno = t . ID and (C.teacherdesc! = T.TEACHERDESC or C.teachername! = t.teachername); Select C.teacherdesc, C.teachername, T.teache Rdesc, T.teachername from course C, teacher t where C.teacherno = t.id;

　　

Oracle Multi-Table Association update