4-1-17');
Query OK, 1 row affected (0.00 sec)
mysql> select * from regusers;
+--------+----------+------------+------------+
| userid | username | birth | last_login |
+--------+----------+------------+------------+
| 10000 | allen | 1981-01-01 | 2014-02-02 |
| 10001 | brooks | 1982-04-02 | 2014-04-30 |
| 10002 | curry | 1985-08-12 | 2014-01-17 |
+--------+----------+------------+------------+
3 rows in set (0.00 sec)
mysql> 4. 更新记录，使用update语句更新或修改满足规定条件的记录。update语句格式为：update <表名> set <列名>=<表达式> [,<列名>=<表达式>]... [where <条件>];例如将regusers表中姓名为brooks的记录的记录修改为ben，如下：
mysql> update regusers set username='ben' where username='brooks';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from regusers;
+--------+----------+------------+------------+
| userid | username | birth | last_login |
+--------+----------+------------+------------+
| 10000 | allen | 1981-01-01 | 2014-02-02 |
| 10001 | ben | 1982-04-02 | 2014-04-30 |
| 10002 | curry | 1985-08-12 | 2014-01-17 |
+--------+----------+------------+------------+
3 rows in set (0.01 sec)
mysql>
5. 删除记录。使用delete语句删除数据表中满足指定条件的记录。delete语句的语法为：delete from <表名> [where <条件>]; 例如删除表中userid为10002的的记录如下：
mysql> delete from regusers where userid=10002;
Query OK, 1 row affected (0.02 sec)
mysql> select * from regusers;
+--------+----------+------------+------------+
| userid | username | birth | last_login |
+--------+----------+------------+------------+
| 10000 | allen | 1981-01-01 | 2014-02-02 |
| 10001 | ben | 1982-04-02 | 2014-04-30 |
+--------+----------+------------+------------+
2 rows in set (0.00 sec)
mysql>
数据库查询操作：sql使用select语句实现数据库的查询。查询是数据库使用最为频繁的操作。select可以查询表中指定满足条件的若干列，同时可对查询结果按一定顺序排序。
查询表tb_users中所有记录sql如下：
mysql> select * from tb_users;
+--------+----------+------------+------------+
| userid | username | birth | last_login |
+--------+----------+------------+------------+
| 10000 | allen | 1981-01-01 | 2014-02-02 |
| 10001 | ben | 1982-04-02 | 2014-04-30 |
| 10002 | curry | 1985-08-12 | 2014-01-17 |
+--------+----------+------------+------------+
3 rows in set (0.00 sec)
查询出生年月小于1983-1-1的所有用户：
mysql> select * from tb_users where birth < '1983-1-1';
+--------+----------+------------+------------+
| userid | username | birth | last_login |
+--------+----------+------------+------------+
| 10000 | allen | 1981-01-01 | 2014-02-02 |
| 10001 | ben | 1982-04-02 | 2014-04-30 |
+--------+----------+------------+------------+
2 rows in set (0.00 sec)
查询出生年月大于1982-1-1，并且按最后登录时间排序：
mysql> select * from tb_users where birth > '1982-1-1' order by last_login;
+--------+----------+------------+------------+
| userid | username | birth | last_login |
+--------+----------+------------+------------+
| 10002 | curry | 1985-08-12 | 2014-01-17 |
| 10001 | ben | 1982-04-02 | 2014-04-30 |
+--------+----------+------------+------------+
2 rows in set (0.00 sec)
只显示用户及其最后登录时间：
mysql> select username,last_login from tb_users;
+----------+------------+
| username | last_login |
+----------+------------+
| allen | 2014-02-02 |
| ben | 2014-04-30 |
| curry | 2014-01-17 |
+----------+------------+
3 rows in set (0.00 sec)