【DB2】经典SQL写法

1.环境准备

CREATE TABLE DataInfo(
ID_1 VARCHAR(10),
ID_2 VARCHAR(10)
)


INSERT INTO DataInfo VALUES('A','Oracle');
INSERT INTO DataInfo VALUES('B','sqlserver');
INSERT INTO DataInfo VALUES('C','DB2');
INSERT INTO DataInfo VALUES('DB2','C');
INSERT INTO DataInfo VALUES('Oracle','A');
INSERT INTO DataInfo VALUES('sqlserver','B');

图表数据展示：

ID_1	ID_2
A	Oracle
B	sqlserver
C	DB2
DB2	C
Oracle	A
sqlserver	B

2.SQL查询

现在判定A,ORACLE与ORACLE,A这种数据为重复数据。

--删除重复数据

DELETE FROM DataInfo A WHERE EXISTS (SELECT 1 FROM DataInfo B WHERE A.ID_1=B.ID_2 AND A.ID_2=B.ID_1)
AND A.ID_1>A.ID_2
ORDER BY ID_2