SQL中进行交差表查询的方法和代码

交叉查询你可以通过两中方法实现

建表语句：注意数据库为sqlserver
create table A(aID int,aNum nvarchar(10))

insert into A (aID,aNum) values (1,'a1')
insert into A (aID,aNum) values (2,'a2')

create table B(bID int,bName nvarchar(10))

insert into B (bID,bName) values (1,'b1')
insert into B (bID,bName) values (2,'b2')
insert into B (bID,bName) values (3,'b3')

create table C(ca int,cb int)

insert into C (ca,cb) values (1,2)
insert into C (ca,cb) values (1,3)
insert into C (ca,cb) values (2,1)
insert into C (ca,cb) values (2,3)
第一：通过full join
select aa.*,cc.*,bb.* from A aa
full join B bb on 1=1
full join C cc on cc.ca=aa.aID and cc.cb=bb.bID

得到的结果是
aID aNum ca cb bID bName
----------- ---------- ----------- ----------- ----------- ----------
1 a1 NULL NULL