DQL

条件查询：

代码实现：

mysql> select name,id,sex 性别 from stu where id != 1;
+--------+------+------+
| name   | id   | 性别 |
+--------+------+------+
| 小程   | 2    | 男   |
| 哈哈哈 | 3    | 男   |
| hhh    | 4    | 女   |
| wuwuwu | 5    | 女   |
+--------+------+------+
4 rows in set (0.00 sec)

mysql> select * from stu where id<3 and name like "小%";
+------+------+------+
| name | id   | sex  |
+------+------+------+
| 小爽 | 1    | 女   |
| 小程 | 2    | 男   |
+------+------+------+
2 rows in set (0.00 sec)

mysql> insert into stu values("aaaa",null,"女");
Query OK, 1 row affected (0.01 sec)

mysql> select * from stu where id is null;
+------+------+------+
| name | id   | sex  |
+------+------+------+
| aaaa | NULL | 女   |
+------+------+------+
1 row in set (0.01 sec)

mysql> select * from stu where id is not null;
+--------+------+------+
| name   | id   | sex  |
+--------+------+------+
| xue    | 1    | 男   |
| 小爽   | 1    | 女   |
| 小程   | 2    | 男   |
| 哈哈哈 | 3    | 男   |
| hhh    | 4    | 女   |
| wuwuwu | 5    | 女   |
+--------+------+------+
6 rows in set (0.00 sec)

mysql> select * from stu where id in (3,4,5);
+--------+------+------+
| name   | id   | sex  |
+--------+------+------+
| 哈哈哈 | 3    | 男   |
| hhh    | 4    | 女   |
| wuwuwu | 5    | 女   |
+--------+------+------+
3 rows in set (0.00 sec)

排序查询

代码实现：

mysql> select * from stu order by id desc;
+--------+------+------+
| name   | id   | sex  |
+--------+------+------+
| wuwuwu | 5    | 女   |
| hhh    | 4    | 女   |
| 哈哈哈 | 3    | 男   |
| 小程   | 2    | 男   |
| xue    | 1    | 男   |
| 小爽   | 1    | 女   |
| aaaa   | NULL | 女   |
+--------+------+------+
7 rows in set (0.01 sec)

聚合函数

分组查询

分页查询