SQL再学习plus++
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)