关于mysql中一条sql语句

发布网友发布时间：2022-04-26 03:59

共3个回答

热心网友时间：2022-05-06 18:30

CREATE TABLE a (code varchar(8));
CREATE TABLE b (code varchar(8));

INSERT INTO a VALUES('A1');
INSERT INTO a VALUES('A2');
INSERT INTO a VALUES('A3');
INSERT INTO a VALUES('A4');
INSERT INTO a VALUES('A5');
INSERT INTO a VALUES('A6');
INSERT INTO a VALUES('A7');
INSERT INTO a VALUES('A8');
INSERT INTO a VALUES('A9');
INSERT INTO a VALUES('A0');

INSERT INTO b VALUES('B1');
INSERT INTO b VALUES('B2');
INSERT INTO b VALUES('B3');
INSERT INTO b VALUES('B4');
INSERT INTO b VALUES('B5');
INSERT INTO b VALUES('B6');
INSERT INTO b VALUES('B7');
INSERT INTO b VALUES('B8');
INSERT INTO b VALUES('B9');
INSERT INTO b VALUES('B0');

-- 错误的写法：
mysql> SELECT * FROM a LIMIT 5
    -> UNION ALL
    -> SELECT * FROM b LIMIT 10;
+------+
| code |
+------+
| A1   |
| A2   |
| A3   |
| A4   |
| A5   |
| B1   |
| B2   |
| B3   |
| B4   |
| B5   |
+------+
10 rows in set (0.00 sec)

-- 正确的写法：
mysql> (SELECT * FROM a LIMIT 5)
    -> UNION ALL
    -> (SELECT * FROM b LIMIT 10);
+------+
| code |
+------+
| A1   |
| A2   |
| A3   |
| A4   |
| A5   |
| B1   |
| B2   |
| B3   |
| B4   |
| B5   |
| B6   |
| B7   |
| B8   |
| B9   |
| B0   |
+------+
15 rows in set (0.00 sec)

热心网友时间：2022-05-06 19:48

如果两个表结构一样可以用UNION连起来

SELECT * FROM table1 LIMIT 5
UNION ALL
SELECT * FROM table2 LIMIT 10

热心网友时间：2022-05-06 21:23

这两个表关系呢？追问没什么关系，就是表结构一样

追答表结构一样楼下正解