MySQL中数据表的查操作

Posted 2020-10-22 llguanli

查询数据表的全部内容

mysql> show tables;#查看当前数据库下的全部表
+--------------------+
| Tables_in_ceshi_ku |
+--------------------+
| biao               |
| ceshi_biao         |
+--------------------+
2 rows in set (0.00 sec)

mysql> select * from biao;#查看该表全部的内容，*代表通配符，在这里是代表全部的列
+------+-----------+--------+----------+--------+
| id   | name      | gender | gongsi   | gongzi |
+------+-----------+--------+----------+--------+
|    1 | ma yun    | n      | tao bao  | 6000.5 |
|    2 | xiao hong | v      | xin lang | 5000.7 |
|    3 | xiao ming | n      | bai du   | 3000.4 |
|    4 | li si     | n      | sou hu   | 9000.2 |
|    5 | lao wang  | NULL   | wang yi  | 1000.5 |
|    6 | xiao li   | NULL   | ku gou   |  700.1 |
+------+-----------+--------+----------+--------+
6 rows in set (0.00 sec)

查询数据表的全部列、部分行

mysql> select * from biao where id>4;#查询全部列，部分行。即id大于4的行
+------+----------+--------+---------+--------+
| id   | name     | gender | gongsi  | gongzi |
+------+----------+--------+---------+--------+
|    5 | lao wang | NULL   | wang yi | 1000.5 |
|    6 | xiao li  | NULL   | ku gou  |  700.1 |
+------+----------+--------+---------+--------+
2 rows in set (0.02 sec)

查询数据表的部分列、全部行

mysql> select name,gongzi from biao;#查询部分列，即"name"和"gongzi"列，之间用","隔开。
选择全部行
+-----------+--------+
| name      | gongzi |
+-----------+--------+
| ma yun    | 6000.5 |
| xiao hong | 5000.7 |
| xiao ming | 3000.4 |
| li si     | 9000.2 |
| lao wang  | 1000.5 |
| xiao li   |  700.1 |
+-----------+--------+
6 rows in set (0.02 sec)

查询数据表的部分列、部分行

mysql> select name from biao where gongzi>3000;#选择部分列，即"name"列，也能够多个列。
然后选择工资>3000的行
+-----------+
| name      |
+-----------+
| ma yun    |
| xiao hong |
| xiao ming |
| li si     |
+-----------+
4 rows in set (0.00 sec)