比如:
表A A_1 A_2
QW 1
QE 2
QR 3
QT 4
表B B_1 B_2
a 1
b 2
c 3
d 4
表C C_1 C_2
a 2
b 1
c 3
d 3现在我想得到的结果是
B_2 A_1 C_2 A_1
1 QW 2 QE
2 QE 1 QW
4 QT 3 QR满足的条件就是B1=C1,B2<>C2。
SELECT 怎么写呢
表A A_1 A_2
QW 1
QE 2
QR 3
QT 4
表B B_1 B_2
a 1
b 2
c 3
d 4
表C C_1 C_2
a 2
b 1
c 3
d 3现在我想得到的结果是
B_2 A_1 C_2 A_1
1 QW 2 QE
2 QE 1 QW
4 QT 3 QR满足的条件就是B1=C1,B2<>C2。
SELECT 怎么写呢
(SELECT * FROM B INNER JOIN C ON B1=C1 AND B2<>C2) A1
LEFT JOIN C ON A1.B_2=C.A_2
LEFT JOIN C1 ON A1.C_2=C1.A_2
(select a_1 from a where a.a_2 = b.b_2),
C_2,
(select a_1 from a where a.a_2 = c.c_2)
From B, C
where B1 = C1
and B2 <> C2;