Question

我想用sql语句实现以下查询：A,B,C为三个表，每个表里对应一个字段a,b,c;查询A,B,C三表中满足条件a的1、2

、3位=b，a的4、5、6位=c的所有数据，应该怎么写？

Answer 1

select * from A,B,C where substr(A.a,1,3) = B.b and substr(A.a,4,3) = c;

Answer 2

SELECT A.a FROM A,B,C WHERE SUBSTRING(A.a,1,3)=B.b AND SUBSTRING(A.a,4,3)=C.c

Answer 3

ORACLE:
SELECT * FROM A,B,C WHERE INSTR(substr(a,1,3),b) > 0 or INSTR(substr(a,4,3),c) > 0
SQLSERVER:
SELECT * FROM A,B,C WHERE charindex(substring(a,1,3),b) > 0 or charindex(substring(a,4,3),c) > 0