应该是A left join C left join D left join B吧
select A.a,A.b,A.c,B.d,C.e from A left join C on (A.a=C.a and A.b=C.b and A.c=C.c) left join B on (A.a=B.a and A.b=B.b)
select A.a,A.b,A.c,B.d,C.e from A left join C on (A.a=C.a and A.b=C.b and A.c=C.c) left join B on (A.a=B.a and A.b=B.b)
FROM (A LEFT JOIN B ON A.a = B.a AND A.b = B.b
LEFT JOIN C ON A.a = C.a AND A.b = C.b AND A.c = C.c)
LEFT JOIN D ON C.e = D.e
FROM (A LEFT JOIN B ON A.a = B.a AND A.b = B.b
LEFT JOIN C ON A.a = C.a AND A.b = C.b AND A.c = C.c)
LEFT JOIN D ON C.e = D.e
2、 ** ** ** ** **
A表有三个主键a、b、c
B表有一个主键d和两个外键a、b、c
C表有一个主键e和三个外键a、b、c
D表有一个主键f和一个外键e表的关系为: A -》B 是一对多的关系, A-》C是一对一, C-》D是一对一。现要得表:(DataGrid显示出来) a b c d f1、 * * * * *
2、 ** ** ** ** **要求: 数据不能少。这回不会再错了!!!
UP!
UP!!
UP!!!