CREATE TABLE R(
A char(10) primary key,
B char(10) )CREATE TABLE S(
A char(10) references R(A),
C char(10) )
A char(10) primary key,
B char(10) )CREATE TABLE S(
A char(10) references R(A),
C char(10) )
调试欢乐多
R |╳| S和 S |╳| R 相同R ]╳| S是什么意思?
A char(10) primary key,
B char(10) )CREATE TABLE S(
A char(10) references R(A),
C char(10) )select * from R inner join S on R.A = S.A
select * from R left join S on R.A = S.A