表操作

创建表：

mysql> create table student(
    -> id int(4) not null auto_increment,
    -> name char(8) not null,
    -> primary key(id),
    -> key index_name(name)
    -> );
mysql> show create table studentG
*************************** 1. row ***************************
       Table: student
Create Table: CREATE TABLE `student` (
  `id` int(4) NOT NULL AUTO_INCREMENT,
  `name` char(8) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `index_name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
mysql> desc student;
+-------+---------+------+-----+---------+----------------+
| Field | Type    | Null | Key | Default | Extra          |
+-------+---------+------+-----+---------+----------------+
| id    | int(4)  | NO   | PRI | NULL    | auto_increment |
| name  | char(8) | NO   | MUL | NULL    |                |
+-------+---------+------+-----+---------+----------------+
mysql> select * from student;
Empty set (0.00 sec)

插入数据insert:

mysql> insert into student (id,name) values(1,'kaka');
mysql> select * from student;
+----+------+
| id | name |
+----+------+
|  1 | kaka |
+----+------+
mysql> insert into student (name) values('bobo');
mysql> select * from student;
+----+------+
| id | name |
+----+------+
|  2 | bobo |
|  1 | kaka |
+----+------+
mysql> insert into student values(3,'tom'),(4,'jack');
mysql> select * from student;
+----+------+
| id | name |
+----+------+
|  2 | bobo |
|  4 | jack |
|  1 | kaka |
|  3 | tom  |
+----+------+

查询数据select:

mysql> select id,name from student; #指定id,name列查询
+----+------+
| id | name |
+----+------+
|  2 | bobo |
|  4 | jack |
|  1 | kaka |
|  3 | tom  |
+----+------+
mysql> select id,name from student limit 2; #限制2条查询，默认从表头开始，此次是name列加索引的原因
+----+------+
| id | name |
+----+------+
|  2 | bobo |
|  4 | jack |
+----+------+
mysql> select id,name from student limit 0,2; #限制查询0,2条不包括第0条
+----+------+
| id | name |
+----+------+
|  2 | bobo |
|  4 | jack |
+----+------+
mysql> select id,name from student where id=1;
+----+------+
| id | name |
+----+------+
|  1 | kaka |
+----+------+
mysql> select id,name from student where name='kaka';
+----+------+
| id | name |
+----+------+
|  1 | kaka |
+----+------+
mysql> select id,name from student where id=1 and name='kaka';
+----+------+
| id | name |
+----+------+
|  1 | kaka |
+----+------+
mysql> select id,name from student where id=2 or name='jack';
+----+------+
| id | name |
+----+------+
|  2 | bobo |
|  4 | jack |
+----+------+
mysql> select id,name from student order by id asc; 
+----+------+
| id | name |
+----+------+
|  1 | kaka |
|  2 | bobo |
|  3 | tom  |
|  4 | jack |
+----+------+
mysql> select id,name from student order by name desc;
+----+------+
| id | name |
+----+------+
|  3 | tom  |
|  1 | kaka |
|  4 | jack |
|  2 | bobo |
+----+------+

explain查看select执行情况：

mysql> desc student;
+-------+---------+------+-----+---------+----------------+
| Field | Type    | Null | Key | Default | Extra          |
+-------+---------+------+-----+---------+----------------+
| id    | int(4)  | NO   | PRI | NULL    | auto_increment |
| name  | char(8) | NO   | MUL | NULL    |                |
+-------+---------+------+-----+---------+----------------+
mysql> explain select id,name from student where name='kaka'G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: student
         type: ref
possible_keys: index_name
          key: index_name
      key_len: 24
          ref: const
         rows: 1                name列有索引情况下，只用一条。
        Extra: Using where; Using index
mysql> alter table student drop key index_name;
mysql> desc student;
+-------+---------+------+-----+---------+----------------+
| Field | Type    | Null | Key | Default | Extra          |
+-------+---------+------+-----+---------+----------------+
| id    | int(4)  | NO   | PRI | NULL    | auto_increment |
| name  | char(8) | NO   |     | NULL    |                |
+-------+---------+------+-----+---------+----------------+
mysql> explain select id,name from student where name='kaka'G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: student
         type: ALL
possible_keys: NULL
          key: NULL
      key_len: NULL
          ref: NULL
         rows: 4           #删除索引后用4条
        Extra: Using where

增删表的字段：

mysql> desc student;
+-------+---------+------+-----+---------+----------------+
| Field | Type    | Null | Key | Default | Extra          |
+-------+---------+------+-----+---------+----------------+
| id    | int(4)  | NO   | PRI | NULL    | auto_increment |
| name  | char(8) | NO   |     | NULL    |                |
| sex   | char(4) | NO   |     | NULL    |                |
+-------+---------+------+-----+---------+----------------+
mysql> alter table student add age tinyint(2) not null after name;
mysql> desc student;
+-------+------------+------+-----+---------+----------------+
| Field | Type       | Null | Key | Default | Extra          |
+-------+------------+------+-----+---------+----------------+
| id    | int(4)     | NO   | PRI | NULL    | auto_increment |
| name  | char(8)    | NO   |     | NULL    |                |
| age   | tinyint(2) | NO   |     | NULL    |                |
| sex   | char(4)    | NO   |     | NULL    |                |
+-------+------------+------+-----+---------+----------------+
mysql> desc student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| qq    | varchar(18) | NO   |     | NULL    |                |
| id    | int(4)      | NO   | PRI | NULL    | auto_increment |
| name  | char(8)     | NO   |     | NULL    |                |
| age   | tinyint(2)  | NO   |     | NULL    |                |
| sex   | char(4)     | NO   |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
mysql> select * from student;
+----+----+------+-----+-----+
| qq | id | name | age | sex |
+----+----+------+-----+-----+
|    |  1 | kaka |   0 |     |
|    |  2 | bobo |   0 |     |
|    |  3 | tom  |   0 |     |
|    |  4 | jack |   0 |     |
+----+----+------+-----+-----+
mysql> alter table student drop qq;
mysql> alter table student drop sex;
mysql> alter table student drop age;
mysql> select * from student;       
+----+------+
| id | name |
+----+------+
|  1 | kaka |
|  2 | bobo |
|  3 | tom  |
|  4 | jack |
+----+------+
mysql> alter table student add age tinyint(2) not null,add sex char(4) not null;
mysql> select * from student;
+----+------+-----+-----+
| id | name | age | sex |
+----+------+-----+-----+
|  1 | kaka |   0 |     |
|  2 | bobo |   0 |     |
|  3 | tom  |   0 |     |
|  4 | jack |   0 |     |
+----+------+-----+-----+

更新表的内容：

mysql> update student set age=18,sex='man' where id=1;  
mysql> select * from student;
+----+------+-----+-----+
| id | name | age | sex |
+----+------+-----+-----+
|  1 | kaka |  18 | man |
|  2 | bobo |   0 |     |
|  3 | tom  |   0 |     |
|  4 | jack |   0 |     |
+----+------+-----+-----+

删除表数据：

mysql> delete from student where id=1;
mysql> delete from student where id>3;
mysql> delete from student where name='tom';  
mysql> select * from student;               
+----+------+-----+-----+
| id | name | age | sex |
+----+------+-----+-----+
|  2 | bobo |   0 |     |
+----+------+-----+-----+

　　

更改表名：

mysql> rename table student to student1;
mysql> show tables;
+-------------------+
| Tables_in_oldgirl |
+-------------------+
| student1          |
| test1             |
+-------------------+
mysql> alter table student1 rename to student;
mysql> show tables;
+-------------------+
| Tables_in_oldgirl |
+-------------------+
| student           |
| test1             |
+-------------------+

删除表：

drop table test;

清空表

truncate table test; 更快 清空物理文件
delete from test;  逻辑清楚，按行删