MySQL的增、删、改、查

1.创建一个名为testDB的数据库

mysql> create Database testDB;
Query OK, 1 row affected (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| testDB             |
+--------------------+
5 rows in set (0.00 sec)

在testDB数据库中创建数据表mybook，并定义存储数据内容的结构。分别定义3个字段，其中，长度为15个字符的字符型字段name用来存放图书名称，整型字段price和pages分别存储图书的价格和页数。

mysql> use testDB;
Database changed
mysql> create table mybook(name char(15), price int, pages int);
Query OK, 0 rows affected (0.00 sec)

mysql> describe mybook;
+-------+----------+------+-----+---------+-------+
| Field | Type     | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| name  | char(15) | YES  |     | NULL    |       |
| price | int(11)  | YES  |     | NULL    |       |
| pages | int(11)  | YES  |     | NULL    |       |
+-------+----------+------+-----+---------+-------+
3 rows in set (0.04 sec)

向mybook数据表中插一条图书信息，其中书名为Linux，价格和页数分别是60元和100页。使用select命令查询表单内容时，需要加上想要查询的字段；如果想查看表单中的所有内容，则可以使用星号（*）通配符来显示

mysql> insert into mybook(name,price,pages) values(‘Linux‘,‘60‘,‘100‘);
Query OK, 1 row affected (0.00 sec)

mysql> select * from mybook;
+-------+-------+-------+
| name  | price | pages |
+-------+-------+-------+
| Linux |    60 |   100 |
+-------+-------+-------+
1 row in set (0.00 sec)

使用update命令将刚才插入的Linux图书信息的价格修改为55元

mysql> update mybook set price=55 where name=Linux;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select name,price from mybook;
+-------+-------+
| name  | price |
+-------+-------+
| Linux |    55 |
+-------+-------+
1 row in set (0.00 sec)

使用delete命令删除数据表mybook中的所有内容，然后再查看该表单中的内容，可以发现该表单内容为空了。

mysql> delete from mybook;
Query OK, 1 row affected (0.00 sec)

mysql> select * from mybook;
Empty set (0.00 sec)

下面使用insert插入命令依次插入4条图书信息

mysql> insert into mybook(name,price,pages) values(‘Linux1‘,‘30‘,‘100‘);
Query OK, 1 row affected (0.00 sec)

mysql> insert into mybook(name,price,pages) values(‘Linux2‘,‘40‘,‘200‘);
Query OK, 1 row affected (0.00 sec)

mysql> insert into mybook(name,price,pages) values(‘Linux3‘,‘50‘,‘300‘);
Query OK, 1 row affected (0.00 sec)

mysql> insert into mybook(name,price,pages) values(‘Linux4‘,‘60‘,‘400‘);
Query OK, 1 row affected (0.00 sec)

分别在mybook数据表中查找出价格大于35元或价格不等于50元的图书

mysql> select * from mybook where price>35;
+--------+-------+-------+
| name   | price | pages |
+--------+-------+-------+
| Linux2 |    40 |   200 |
| Linux3 |    50 |   300 |
| Linux4 |    60 |   400 |
+--------+-------+-------+
3 rows in set (0.00 sec)

mysql> select * from mybook where price!=50;
+--------+-------+-------+
| name   | price | pages |
+--------+-------+-------+
| Linux1 |    30 |   100 |
| Linux2 |    40 |   200 |
| Linux4 |    60 |   400 |
+--------+-------+-------+
3 rows in set (0.00 sec)

批量删除多条记录

mysql> select * from mybook;
+--------+-------+-------+
| name   | price | pages |
+--------+-------+-------+
| Linux1 |    30 |   100 |
| Linux2 |    40 |   200 |
| Linux3 |    50 |   300 |
| Linux4 |    60 |   400 |
+--------+-------+-------+
4 rows in set (0.00 sec)

mysql> delete from mybook where name in (‘Linux1‘,‘Linux3‘);
Query OK, 2 rows affected (0.00 sec)

mysql> select * from mybook;
+--------+-------+-------+
| name   | price | pages |
+--------+-------+-------+
| Linux2 |    40 |   200 |
| Linux4 |    60 |   400 |
+--------+-------+-------+
2 rows in set (0.00 sec)

MySQL的增、删、改、查

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