高级查询
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MySQL提供了几种高级查询语句，用于复杂场所下进行多表一起查询，这样就会用到内连接查询、外连接查询、自然连接查询、交叉连接查询和联合查询，以满足日常业务查询的需求，从而更能体会MySQL强大的功能。
1、内连接查询
SELECT*FROM 左表 [INNER] JOIN 右表 ON 左表.字段=右表.字段；
mysql> select*from user;
+----+-------+------+------+----------+---------+-----------+
| id | name | sex | age | password | phone | loginname |
+----+-------+------+------+----------+---------+-----------+
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj |
+----+-------+------+------+----------+---------+-----------+
5 rows in set (0.00 sec)
mysql> use shop;
Database changed
mysql> create table score(
-> id int not null,
-> score nvarchar(233),
-> grage nvarchar(233),
-> primary key(id));
Query OK, 0 rows affected (0.07 sec)
mysql> insert into score values(1,'88','优秀');
Query OK, 1 row affected (0.02 sec)
mysql> insert into score values(2,'70','中等');
Query OK, 1 row affected (0.02 sec)
mysql> insert into score values(3,'60','不优秀');
Query OK, 1 row affected (0.02 sec)
mysql> select*from score;
+----+-------+--------+
| id | score | grage |
+----+-------+--------+
| 1 | 88 | 优秀 |
| 2 | 70 | 中等 |
| 3 | 60 | 不优秀 |
+----+-------+--------+
3 rows in set (0.02 sec)
mysql> select*from user u inner join score s on u.id=s.id;
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| id | name | sex | age | password | phone | loginname | id | score | grage |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 1 | 88 | 优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 2 | 70 | 中等 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 3 | 60 | 不优秀 |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
3 rows in set (0.02 sec)
mysql> select*from user u join score s on u.id=s.id;
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| id | name | sex | age | password | phone | loginname | id | score | grage |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 1 | 88 | 优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 2 | 70 | 中等 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 3 | 60 | 不优秀 |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
3 rows in set (0.00 sec)
mysql> select u.id uid,u.name,u.sex,u.age,s.score,s.grage from user u join score s on u.id=s.id;
+-----+-------+------+------+-------+--------+
| uid | name | sex | age | score | grage |
+-----+-------+------+------+-------+--------+
| 1 | david | 男 | 19 | 88 | 优秀 |
| 2 | 小明 | 男 | 22 | 70 | 中等 |
| 3 | 小花 | 女 | 21 | 60 | 不优秀 |
+-----+-------+------+------+-------+--------+
3 rows in set (0.00 sec)
mysql> select u.id uid,u.name,u.sex,u.age,s.score,s.grage from user u join score s u.id=s.id;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'u.id=s.id' at line 1
mysql> select*from user u join score s;
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| id | name | sex | age | password | phone | loginname | id | score | grage |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 1 | 88 | 优秀 |
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 2 | 70 | 中等 |
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 3 | 60 | 不优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 1 | 88 | 优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 2 | 70 | 中等 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 3 | 60 | 不优秀 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 1 | 88 | 优秀 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 2 | 70 | 中等 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 3 | 60 | 不优秀 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 1 | 88 | 优秀 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 2 | 70 | 中等 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 3 | 60 | 不优秀 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 1 | 88 | 优秀 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 2 | 70 | 中等 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 3 | 60 | 不优秀 |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
15 rows in set (0.00 sec)
mysql> select*from user u inner join score s on u.id=s.id;
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| id | name | sex | age | password | phone | loginname | id | score | grage |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 1 | 88 | 优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 2 | 70 | 中等 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 3 | 60 | 不优秀 |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
3 rows in set (0.00 sec)
mysql> select*from user u inner join score s on u.id>s.id;
+----+------+------+------+----------+---------+-----------+----+-------+--------+
| id | name | sex | age | password | phone | loginname | id | score | grage |
+----+------+------+------+----------+---------+-----------+----+-------+--------+
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 1 | 88 | 优秀 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 1 | 88 | 优秀 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 2 | 70 | 中等 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 1 | 88 | 优秀 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 2 | 70 | 中等 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 3 | 60 | 不优秀 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 1 | 88 | 优秀 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 2 | 70 | 中等 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 3 | 60 | 不优秀 |
+----+------+------+------+----------+---------+-----------+----+-------+--------+
9 rows in set (0.00 sec)
2、外连接查询
SELECT * FROM 左表 LEFT/RIGHT JOIN 右表 ON 左表.字段=右表.字段；
mysql> select*from user u left join score s on u.id=s.id;左
+----+-------+------+------+----------+---------+-----------+------+-------+--------+
| id | name | sex | age | password | phone | loginname | id | score | grage |
+----+-------+------+------+----------+---------+-----------+------+-------+--------+
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 1 | 88 | 优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 2 | 70 | 中等 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 3 | 60 | 不优秀 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | NULL | NULL | NULL |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | NULL | NULL | NULL |
+----+-------+------+------+----------+---------+-----------+------+-------+--------+
5 rows in set (0.02 sec)
mysql> select*from user u right join score s on u.id=s.id;右
+------+-------+------+------+----------+---------+-----------+----+-------+--------+
| id | name | sex | age | password | phone | loginname | id | score | grage |
+------+-------+------+------+----------+---------+-----------+----+-------+--------+
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 1 | 88 | 优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 2 | 70 | 中等 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 3 | 60 | 不优秀 |
+------+-------+------+------+----------+---------+-----------+----+-------+--------+
3 rows in set (0.00 sec)
3、交叉连接查询
SELECT *左表 CROSS JOIN 右表 或 FROM 左表，右表；
mysql> select*from user cross join score;交叉连接
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| id | name | sex | age | password | phone | loginname | id | score | grage |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 1 | 88 | 优秀 |
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 2 | 70 | 中等 |
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 3 | 60 | 不优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 1 | 88 | 优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 2 | 70 | 中等 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 3 | 60 | 不优秀 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 1 | 88 | 优秀 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 2 | 70 | 中等 |
| 3 | 小花 | 女 | 21 | 123456 | 666。6666 | hfhhkj | 3 | 60 | 不优秀 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 1 | 88 | 优秀 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 2 | 70 | 中等 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 3 | 60 | 不优秀 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 1 | 88 | 优秀 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 2 | 70 | 中等 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 3 | 60 | 不优秀 |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
15 rows in set (0.00 sec)
mysql> select*from user,score;from两个表
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| id | name | sex | age | password | phone | loginname | id | score | grage |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 1 | 88 | 优秀 |
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 2 | 70 | 中等 |
| 1 | david | 男 | 19 | 123456 | 5555555 | hfhhj | 3 | 60 | 不优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 1 | 88 | 优秀 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 2 | 70 | 中等 |
| 2 | 小明 | 男 | 22 | 123456 | 444444 | hfhhj | 3 | 60 | 不优秀 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 1 | 88 | 优秀 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 2 | 70 | 中等 |
| 3 | 小花 | 女 | 21 | 123456 | 6666666 | hfhhkj | 3 | 60 | 不优秀 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 1 | 88 | 优秀 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 2 | 70 | 中等 |
| 4 | 小敏 | 女 | 25 | 123456 | 8888888 | hfhhj | 3 | 60 | 不优秀 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 1 | 88 | 优秀 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 2 | 70 | 中等 |
| 5 | 小华 | 男 | 26 | 123456 | 999999 | hfhhj | 3 | 60 | 不优秀 |
+----+-------+------+------+----------+---------+-----------+----+-------+--------+
15 rows in set (0.00 sec)
4、联合查询
SELECT column_name FROM table1
UNION (all)
SELECT column_name FROM table2；
mysql> select id from user;
+----+
| id |
+----+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
+----+
5 rows in set (0.00 sec)
mysql> select id from user 集合
-> union
-> select id from score;
+----+
| id |
+----+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
+----+
5 rows in set (0.02 sec)
mysql> select id,name from user
-> union
-> select id,score from score;
+----+-------+
| id | name |
+----+-------+
| 1 | david |
| 2 | 小明 |
| 3 | 小花 |
| 4 | 小敏 |
| 5 | 小华 |
| 1 | 88 |
| 2 | 70 |
| 3 | 60 |
+----+-------+
8 rows in set (0.00 sec)
