SQL语句中EXISTS的详细用法大全
作者:zhangbeizhen18 时间:2024-01-22 11:09:11
前言
在业务开展中,会遇到类似需求。
需求1:UPDATE表TEST_TB01中的记录;满足条件:这些记录不在TEST_TB02中。
需求2:UPDATE表TEST_TB01中的记录;满足条件:这些记录在TEST_TB02中。
在SQL语句中EXISTS的用法,能够比较简洁的去解决这类需求。
一、建表
1.在MySQL数据库建表语句
CREATE TABLE TEST_TB01
(
sensor_id BIGINT,
part_id BIGINT,
flag VARCHAR(64)
)
COMMENT '数据表一';
CREATE TABLE TEST_TB02
(
sensor_id BIGINT,
part_id BIGINT,
flag VARCHAR(64)
)
COMMENT '数据表二';
CREATE TABLE TEST_TB03
(
sensor_id BIGINT,
part_id BIGINT,
flag VARCHAR(64)
)
COMMENT '数据表三';
2.在ORACLE数据库建表语句
CREATE TABLE TEST_TB01
(
sensor_id NUMBER(16),
part_id NUMBER(16),
flag VARCHAR(64)
);
CREATE TABLE TEST_TB02
(
sensor_id NUMBER(16),
part_id NUMBER(16),
flag VARCHAR(64)
);
二、在SELECT语句中使用EXISTS
在SELECT的SQL语句中使用EXISTS。
在TEST_TB01插入数据:
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2101,8811,'厦门');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2102,8812,'泉州');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2103,8813,'福州');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2104,8814,'漳州');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2105,8815,'杭州');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2106,8816,'上海');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2107,8817,'北京');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2108,8818,'深圳');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2109,8819,'中国');
在TEST_TB02插入数据:
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2101,8811,'厦门');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2102,8812,'泉州');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2103,8813,'福州');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2104,8814,'漳州');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2109,8819,'中国');
在TEST_TB03插入数据:
INSERT INTO TEST_TB03 (sensor_id,part_id,flag) VALUES(2106,8816,'上海');
INSERT INTO TEST_TB03 (sensor_id,part_id,flag) VALUES(2107,8817,'北京');
INSERT INTO TEST_TB03 (sensor_id,part_id,flag) VALUES(2109,8819,'中国');
查看TEST_TB01数据:
查看TEST_TB02数据:
查看TEST_TB03数据:
1.在SQL中使用EXISTS
需求:从TEST_TB01中查询出在TEST_TB02中存在的记录,关联条件是两个表的sensor_id相等。
SQL语句:
SELECT
aa.sensor_id,aa.part_id,aa.flag
FROM
TEST_TB01 aa
WHERE EXISTS
(SELECT 1 FROM
TEST_TB02 bb
WHERE aa.sensor_id = bb.sensor_id);
执行结果:
2.在SQL中使用NOT EXISTS
需求:从TEST_TB01中查询出在TEST_TB02中不存在的记录,关联条件是两个表的sensor_id相等。
SQL语句:
SELECT
aa.sensor_id,aa.part_id,aa.flag
FROM
TEST_TB01 aa
WHERE NOT EXISTS
(SELECT 1 FROM
TEST_TB02 bb
WHERE aa.sensor_id = bb.sensor_id);
执行结果:
3.在SQL中使用多个NOT EXISTS
需求:从TEST_TB01中查询出在TEST_TB02和TEST_TB03中都不存在的记录,关联条件是表的sensor_id相等。
SQL语句:
SELECT
aa.sensor_id,aa.part_id,aa.flag
FROM
TEST_TB01 aa
WHERE NOT EXISTS
(SELECT 1 FROM
TEST_TB02 bb
WHERE aa.sensor_id = bb.sensor_id)
AND NOT EXISTS
(SELECT 1 FROM
TEST_TB03 cc
WHERE aa.sensor_id = cc.sensor_id);
执行结果:
4.在SQL中使用多个EXISTS
需求:从TEST_TB01中查询出在TEST_TB02和TEST_TB03中都存在的记录,关联条件是表的sensor_id相等。
SQL语句:
SELECT
aa.sensor_id,aa.part_id,aa.flag
FROM
TEST_TB01 aa
WHERE EXISTS
(SELECT 1 FROM
TEST_TB02 bb
WHERE aa.sensor_id = bb.sensor_id)
AND EXISTS
(SELECT 1 FROM
TEST_TB03 cc
WHERE aa.sensor_id = cc.sensor_id);
执行结果:
5.在SQL中使用NOT EXISTS和EXISTS
需求:从TEST_TB01中查询出在TEST_TB02存在但是TEST_TB03中不存在的记录,关联条件是表的sensor_id相等。
SQL语句:
SELECT
aa.sensor_id,aa.part_id,aa.flag
FROM
TEST_TB01 aa
WHERE EXISTS
(SELECT 1 FROM
TEST_TB02 bb
WHERE aa.sensor_id = bb.sensor_id)
AND NOT EXISTS
(SELECT 1 FROM
TEST_TB03 cc
WHERE aa.sensor_id = cc.sensor_id);
执行结果:
三、在DELETE语句中使用EXISTS
在DELETE的SQL语句中使用EXISTS和NOT EXISTS。
在TEST_TB01插入数据:
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2101,8811,'厦门');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2102,8812,'泉州');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2103,8813,'福州');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2104,8814,'漳州');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2105,8815,'杭州');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2106,8816,'上海');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2107,8817,'北京');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2108,8818,'深圳');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2109,8819,'中国');
在TEST_TB02插入数据:
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2101,8811,'厦门');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2102,8812,'泉州');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2103,8813,'福州');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2104,8814,'漳州');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2109,8819,'中国');
1.在MySQL中使用
需求:从TEST_TB01中删除在TEST_TB02中存在的记录,关联条件是两个表的sensor_id相等。
注意:本例使用MySQL版本:MySQL 5.7.33。
SQL语句:
DELETE FROM
TEST_TB01 aa
WHERE EXISTS
(SELECT 1 FROM
TEST_TB02 bb
WHERE aa.sensor_id = bb.sensor_id);
执行结果:
结论:在MySQL中是不支持在DELETE的SQL语句中使用EXISTS和NOT EXISTS这种句法。(本例版本:MySQL 5.7.33)。
解决此需求:
SQL语句:
DELETE
aa
FROM
TEST_TB01 aa
INNER JOIN TEST_TB02 bb
ON aa.sensor_id = bb.sensor_id;
注意:在SQL中DELETE后面紧跟着的是需求中需要删除的表名的别名。
如果不使用别名会报错:
2.在Oracle中使用
需求:从TEST_TB01中删除在TEST_TB02中存在的记录,关联条件是两个表的sensor_id相等。
SQL语句:
DELETE FROM
TEST_TB01 aa
WHERE EXISTS
(SELECT 1 FROM
TEST_TB02 bb
WHERE aa.sensor_id = bb.sensor_id);
执行结果:
执行前TEST_TB01:
执行前TEST_TB02:
执行后TEST_TB01:
四、在UPDATE语句中使用EXISTS
在UPDATE的SQL语句中使用EXISTS。
在TEST_TB01插入数据:
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2101,8811,'城市');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2102,8812,'城市');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2103,8813,'城市');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2104,8814,'城市');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2105,8815,'城市');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2106,8816,'城市');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2107,8817,'城市');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2108,8818,'城市');
INSERT INTO TEST_TB01 (sensor_id,part_id,flag) VALUES(2109,8819,'城市');
在TEST_TB02插入数据:
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2101,8811,'厦门');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2102,8812,'泉州');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2103,8813,'福州');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2104,8814,'漳州');
INSERT INTO TEST_TB02 (sensor_id,part_id,flag) VALUES(2109,8819,'中国');
1.在MySQL中使用
需求:在TEST_TB01中更新,在TEST_TB02中存在的记录,关联条件是两个表的sensor_id相等。
注意:本例使用MySQL版本:MySQL 5.7.33。
SQL语句:
UPDATE TEST_TB01 aa
SET (aa.part_id, aa.flag) =
(SELECT bb.part_id, bb.flag
FROM TEST_TB02 bb
WHERE aa.sensor_id = bb.sensor_id)
WHERE EXISTS
(SELECT 1 FROM TEST_TB02 cc
WHERE aa.sensor_id = cc.sensor_id);
执行结果:
结论:在MySQL中是不支持在UPDATE的SQL语句中使用EXISTS和NOT EXISTS这种句法。(本例版本:MySQL 5.7.33)。
解决此需求:
SQL语句:
UPDATE TEST_TB01 aa ,TEST_TB02 bb
SET
aa.part_id=bb.part_id,
aa.flag=bb.flag
WHERE aa.sensor_id = bb.sensor_id;
执行结果:
执行前TEST_TB01:
执行前TEST_TB02:
执行后TEST_TB01:
2.在Oracle中使用
需求:在TEST_TB01中更新,在TEST_TB02中存在的记录,关联条件是两个表的sensor_id相等。
SQL语句:
UPDATE TEST_TB01 aa
SET (aa.part_id, aa.flag) =
(SELECT bb.part_id, bb.flag
FROM TEST_TB02 bb
WHERE aa.sensor_id = bb.sensor_id)
WHERE EXISTS
(SELECT 1 FROM TEST_TB02 cc
WHERE aa.sensor_id = cc.sensor_id);
执行结果:
执行前TEST_TB01:
执行前TEST_TB02:
执行后TEST_TB01:
以上,感谢。
来源:https://blog.csdn.net/zhangbeizhen18/article/details/119060431