小编给大家分享一下MySQL如何管理创建CREATE表和索引，希望大家阅读完这篇文章之后都有所收获，下面让我们一起去探讨吧！
SQL语句：
数据库
表
索引
视图
DML语句
单字段：
PRIMARY KEY 主键
UNIQUE KEY 唯一键
单或者多字段：
PRIMARY KEY(col,...)
UNIQUE KEY(col,...)
INDEX(col,...)
数据类型：
data_type:
BIT[(length)] 比特
| TINYINT[(length)] [UNSIGNED] [ZEROFILL] 非常小的整数（1字节）
| SMALLINT[(length)] [UNSIGNED] [ZEROFILL]小的整数（2字节）
| MEDIUMINT[(length)] [UNSIGNED] [ZEROFILL]中等的整数（3字节）
| INT[(length)] [UNSIGNED] [ZEROFILL] 整数（4字节）
| INTEGER[(length)] [UNSIGNED] [ZEROFILL]整数（4字节）相当于INT
| BIGINT[(length)] [UNSIGNED] [ZEROFILL]大的整数（8个字节）
| REAL[(length,decimals)] [UNSIGNED] [ZEROFILL]实数
| DOUBLE[(length,decimals)] [UNSIGNED] [ZEROFILL]双数
| FLOAT[(length,decimals)] [UNSIGNED] [ZEROFILL]浮点型
| DECIMAL[(length[,decimals])] [UNSIGNED] [ZEROFILL]十进制小数点型
| NUMERIC[(length[,decimals])] [UNSIGNED] [ZEROFILL]数值型
| DATE 日期型
| TIME 时间型
| TIMESTAMP 时区型
| DATETIME 日期时间型
| YEAR 年
| CHAR[(length)] 定长字符型
VARCHAR(length)变长字符型
[CHARACTER SET charset_name] [COLLATE collation_name]
| BINARY[(length)]二进制数
| VARBINARY(length)变长二进制数
| TINYBLOB 非常小的大对数
| BLOB 大对数
| MEDIUMBLOB 中等的大对数
| LONGBLOB 长的大对数
| TINYTEXT [BINARY]非常小的文本串
[CHARACTER SET charset_name] [COLLATE collation_name]
| TEXT [BINARY]文本串
[CHARACTER SET charset_name] [COLLATE collation_name]
| MEDIUMTEXT [BINARY]中等的文本串
[CHARACTER SET charset_name] [COLLATE collation_name]
| LONGTEXT [BINARY]长的文本串
[CHARACTER SET charset_name] [COLLATE collation_name]
| ENUM(value1,value2,value3,...)枚举型
[CHARACTER SET charset_name] [COLLATE collation_name]
| SET(value1,value2,value3,...)集合型
[CHARACTER SET charset_name] [COLLATE collation_name]
| spatial_type 空间的类型
1、创建数据库：
CREATE DATABASE|SCHEMA [IF NOT EXISTS] db_name [CHARACTER SET=] [COLLATE]
创建数据库可以设置字符集，排序规则
mysql> SHOW CHARACTER SET; #查看字符集
+----------+-----------------------------+---------------------+--------+
| Charset | Description | Default collation | Maxlen |
+----------+-----------------------------+---------------------+--------+
.......
| big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 |
| tis620 | TIS620 Thai | tis620_thai_ci | 1 |
| cp1250 | Windows Central European | cp1250_general_ci | 1 |
| gbk | GBK Simplified Chinese | gbk_chinese_ci | 2 |
| macroman | Mac West European | macroman_general_ci | 1 |
| cp852 | DOS Central European | cp852_general_ci | 1 |
| latin7 | ISO 8859-13 Baltic | latin7_general_ci | 1 |
| utf8mb4 | UTF-8 Unicode | utf8mb4_general_ci | 4 |
| cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
........
+----------+-----------------------------+---------------------+--------+
39 rows in set (0.00 sec)
mysql> SHOW COLLATION; #查看排序规则
+--------------------------+----------+-----+---------+----------+---------+
| Collation | Charset | Id | Default | Compiled | Sortlen |
+--------------------------+----------+-----+---------+----------+---------+
| big5_chinese_ci | big5 | 1 | Yes | Yes | 1 |
| big5_bin | big5 | 84 | | Yes | 1 |
| cp1250_polish_ci | cp1250 | 99 | | Yes | 1 |
| gbk_chinese_ci | gbk | 28 | Yes | Yes | 1 |
| gbk_bin | gbk | 87 | | Yes | 1 |
| latin5_turkish_ci | latin5 | 30 | Yes | Yes | 1 |
+--------------------------+----------+-----+---------+----------+---------+
197 rows in set (0.00 sec)
mysql> CREATE DATABASE IF NOT EXISTS students CHARACTER SET 'gbk' COLLATE 'gbk_chinese_ci';
#创建一个students数据库，字符集为gbk，排序规则为gbk_chinese_ci
Query OK, 1 row affected (0.01 sec)
mysql> \q
Bye
[root@lamp ~]# ls /mydata/data #查看students是否新建成功
ib_logfile1 mysql-bin.000001 mysql-bin.000006 mysql-bin.000011 students
lamp.err mysql-bin.000002 mysql-bin.000007 mysql-bin.000012 test
[root@lamp ~]# file /mydata/data/students/db.opt #查看students数据库中db.opt文件类型
/mydata/data/students/db.opt: ASCII text
2、修改数据库：
ALTER {DATABASE | SCHEMA} [db_name] alter_specification ...#修改数据库的属性，比如字符集或者排序规则，alter_specification CHARACTER SET = charset_name COLLATE = collation_name
alter_specification包含:
[DEFAULT] CHARACTER SET [=] charset_name
| [DEFAULT] COLLATE [=] collation_name
ALTER {DATABASE | SCHEMA} db_name UPGRADE DATA DIRECTORY NAME #升级数据库的数据目录
3、删除数据库：
DROP {DATABASE | SCHEMA} [IF EXISTS] db_name #删除数据库
4、创建表：
1.直接定义一张空表；col_name 字段名称 col_defination 字段定义
CREATE TABLE [IF NOT EXISTS] tb_name (col_name col_defination,)
col_defination字段定义包含：data_type字段类型
data_type [NOT NULL | NULL] [DEFAULT default_value]
[AUTO_INCREMENT] [UNIQUE [KEY] | [PRIMARY] KEY]
[COMMENT 'string']
[COLUMN_FORMAT {FIXED|DYNAMIC|DEFAULT}]
[STORAGE {DISK|MEMORY|DEFAULT}]
[reference_definition]
Usage:CREATE TABLE tb1(id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,Name CHAR(20) NOT NULL,Age TINYINT NOT NULL);#创建一个表tb1，包含三个字段:id字段为无符号(UNSIGNED)，非空(NOT NULL)，自动增长(AUTO_INCREMENT)，为主键(PRIMARY KEY)的整型.Name字段为定长20(CHAR(20)),非空的字符型。Age字段为非空的非常小的整型。
或者 CREATE TABLE tb2(id INT UNSIGNED NOT NULL AUTO_INCREMENT,Name CHAR(20) NOT NULL,Age TINYINT NOT NULL,PRIMARY KEY(id),Unique KEY (Name),INDEX(age)); Unique KEY 唯一键，INDEX索引
2.从其他表中查询出数据，并以之创建新表；
CREATE TABLE testcourses SELECT * FROM courses WHERE CID <= 2;#从courses表中查找
CID小于等于2的数据，并作为新建testcourses表的内容。
3.以其他表为模板创建一个空表；
CREATE TABLE new_table LIKE old_table; 以old_table表为模板，建立new_table表
查看表索引：
SHOW INDEXES FROM courses; 显示制定表索引
查看表结构：
DESC tb_name; 查看表结构
mysql> DESC courses;
+-------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+----------------+
| CID | tinyint(3) unsigned | NO | PRI | NULL | auto_increment |
| Couse | varchar(50) | NO | | NULL | |
+-------+---------------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
5、修改表定义：ALTER TABLE
添加、删除、修改字段，添加、删除、修改索引，改表名，修改表属性。
mysql> ALTER TABLE test ADD INDEX(Couse); #给test表增加以Couse字段为索引
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> SHOW INDEXES FROM test; #查看test表的索引
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| test | 0 | PRIMARY | 1 | CID | A | 0 | NULL | NULL | | BTREE | | |
| test | 1 | Couse | 1 | Couse | A | NULL | NULL | NULL | | BTREE | | |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
2 rows in set (0.00 sec)
mysql> DESC test; #查看表结构
+-------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+----------------+
| CID | tinyint(3) unsigned | NO | PRI | NULL | auto_increment |
| Couse | varchar(50) | NO | MUL | NULL | |
+-------+---------------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
mysql> ALTER TABLE test CHANGE Couse Course VARCHAR(50) NOT NULL; #修改test表的Couse字段名称为Course并定义为变长50字符长度，非空
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> DESC test; 查看表结构
+--------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------+---------------------+------+-----+---------+----------------+
| CID | tinyint(3) unsigned | NO | PRI | NULL | auto_increment |
| Course | varchar(50) | NO | MUL | NULL | |
+--------+---------------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
mysql> DROP TABLE testcourses; #删除testcourses表
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW TABLES;查看所有表
+--------------------+
| Tables_in_students |
+--------------------+
| courses |
| test |
+--------------------+
2 rows in set (0.00 sec)
mysql> ALTER TABLE test RENAME TO testcourses; #修改test表的名称为testcourses
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW TABLES;查看所有表
+--------------------+
| Tables_in_students |
+--------------------+
| courses |
| testcourses |
+--------------------+
2 rows in set (0.00 sec)
mysql> RENAME TABLE testcourses TO test; #也可以直接使用RENAME重命名。
Query OK, 0 rows affected (0.00 sec)
6、新增索引：（索引只能新建删除，不能修改）
CREATE INDEX index_name ON tb_name (col,...)
col_name (length) ASC|DESC 指定以字段前几的长度为索引，ASC升序排列，
DESC降序排列。
在tb_name表上的col字段创建一个索引index_name
CREATE INDEX name_on_student ON student (Name) USING BTREE;
#在student表中Name字段上建立一个名为name_on_student索引，类型为BTREE索引，默认为BTREE类型。
mysql> CREATE INDEX name_on_student ON student (Name) USING BTREE ;
Query OK, 0 rows affected (0.15 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> SHOW INDEXES FROM student ;
+---------+------------+-----------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------+------------+-----------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| student | 0 | PRIMARY | 1 | SID | A | 4 | NULL | NULL | | BTREE | | |
| student | 1 | foreign_cid | 1 | CID | A | 4 | NULL | NULL | | BTREE | | |
| student | 1 | name_on_student | 1 | Name | A | 4 | NULL | NULL | YES | BTREE | | |
+---------+------------+-----------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
3 rows in set (0.00 sec)
mysql> DROP INDEX name_on_student ON student;#删除student表中的索引name_on_student
Query OK, 0 rows affected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> CREATE INDEX name_on_student ON student (Name(5) DESC);#为student表以Name字段
的前5个字符建立一个降序（DESC）排列的索引.
Query OK, 0 rows affected (0.05 sec)
Records: 0 Duplicates: 0 Warnings: 0
实例1：创建一个students数据库，以及表的创建，查找等功能的练习；
mysql> CREATE DATABASE IF NOT EXISTS students CHARACTER SET 'gbk' COLLATE 'gbk_chinese_ci';
#创建一个students数据库，字符集为gbk，排序规则为gbk_chinese_ci
Query OK, 1 row affected (0.01 sec)
mysql> USE students;
Database changed
mysql> CREATE TABLE courses(CID TINYINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,Couse VARCHAR(50) NOT NULL);
Query OK, 0 rows affected (0.07 sec)
mysql> SHOW TABLE STATUS LIKE 'courses'\G;
*************************** 1. row ***************************
Name: courses
Engine: InnoDB
Version: 10
Row_format: Compact
Rows: 0
Avg_row_length: 0
Data_length: 16384
Max_data_length: 0
Index_length: 0
Data_free: 0
Auto_increment: 1
Create_time: 2017-04-25 10:19:13
Update_time: NULL
Check_time: NULL
Collation: gbk_chinese_ci
Checksum: NULL
Create_options:
Comment:
1 row in set (0.00 sec)
ERROR:
No query specified
mysql> DROP TABLES courses; #删除表
Query OK, 0 rows affected (0.01 sec)
mysql> CREATE TABLE courses(CID TINYINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,Couse VARCHAR(50) NOT NULL) ENGINE=MyISAM; #ENGINE设定引擎为MyISAM
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW TABLE STATUS LIKE 'courses'\G;
*************************** 1. row ***************************
Name: courses
Engine: MyISAM
Version: 10
Row_format: Dynamic
Rows: 0
Avg_row_length: 0
Data_length: 0
Max_data_length: 281474976710655
Index_length: 1024
Data_free: 0
Auto_increment: 1
Create_time: 2017-04-25 10:51:45
Update_time: 2017-04-25 10:51:45
Check_time: NULL
Collation: gbk_chinese_ci
Checksum: NULL
Create_options:
Comment:
1 row in set (0.00 sec)
ERROR:
No query specified
mysql> INSERT INTO courses (Couse) values ('physics'),('english'),('chemistry'),('maths');
#插入Couse课程字段数据，添加物理，英语，化学，数学等课程。
Query OK, 4 rows affected (0.00 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM courses; #查询courses表的条目
+-----+-----------+
| CID | Couse |
+-----+-----------+
| 1 | physics |
| 2 | english |
| 3 | chemistry |
| 4 | maths |
+-----+-----------+
4 rows in set (0.00 sec)
mysql> SHOW INDEXES FROM courses; #查看courses表的索引
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| courses | 0 | PRIMARY | 1 | CID | A | 4 | NULL | NULL | | BTREE | | |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
1 row in set (0.00 sec)
mysql> CREATE TABLE testcourses SELECT * FROM courses WHERE CID <= 2; #查找courses表中CID字段小于等于2的数据，并把查找到的数据作为新建testcourses表的数据内容。
Query OK, 2 rows affected (0.08 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> SHOW TABLES; #查看当前数据库表的信息
+--------------------+
| Tables_in_students |
+--------------------+
| courses |
| testcourses |
+--------------------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM testcourses; #查看testcourses表的内容
+-----+---------+
| CID | Couse |
+-----+---------+
| 1 | physics |
| 2 | english |
+-----+---------+
2 rows in set (0.00 sec)
mysql> DESC courses; #查看courses表结构
+-------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+----------------+
| CID | tinyint(3) unsigned | NO | PRI | NULL | auto_increment |
| Couse | varchar(50) | NO | | NULL | |
+-------+---------------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
mysql> DESC testcourses; #查看testcourses表结构
+-------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+-------+
| CID | tinyint(3) unsigned | NO | | 0 | |
| Couse | varchar(50) | NO | | NULL | |
+-------+---------------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
mysql> CREATE TABLE test LIKE courses; #以courses表为模板创建test空表。
Query OK, 0 rows affected (0.00 sec)
mysql> DESC test; #查看test表结构
+-------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+----------------+
| CID | tinyint(3) unsigned | NO | PRI | NULL | auto_increment |
| Couse | varchar(50) | NO | | NULL | |
+-------+---------------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
mysql> SHOW TABLE STATUS LIKE 'test'\G; #查看test表的状态
*************************** 1. row ***************************
Name: test
Engine: MyISAM
Version: 10
Row_format: Dynamic
Rows: 0
Avg_row_length: 0
Data_length: 0
Max_data_length: 281474976710655
Index_length: 1024
Data_free: 0
Auto_increment: 1
Create_time: 2017-04-25 11:31:46
Update_time: 2017-04-25 11:31:46
Check_time: NULL
Collation: gbk_chinese_ci
Checksum: NULL
Create_options:
Comment:
1 row in set (0.00 sec)
ERROR:
No query specified
实例2.建立student表，并进行相关数据的插入，查询操作练习，修改引擎，修改字段修饰，
增加外键索引；
mysql> CREATE TABLE student (SID INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,Name
VARCHAR(30),CID INT NOT NULL);#创建student表，包含3个字段，SID字段为无符号非空自动增长主键的整数型，Name字段为变长30字符，CID字符为非空整数型。
mysql> SHOW TABLES;
+--------------------+
| Tables_in_students |
+--------------------+
| courses |
| student |
| test |
+--------------------+
3 rows in set (0.00 sec)
mysql> INSERT INTO student (Name,CID) VALUES ('Li Lianjie',1),('Cheng Long',2);#对Name,CID字段插入2条数据。
Query OK, 2 rows affected (0.01 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM student; #查询student表
+-----+------------+-----+
| SID | Name | CID |
+-----+------------+-----+
| 1 | Li Lianjie | 1 |
| 2 | Cheng Long | 2 |
+-----+------------+-----+
2 rows in set (0.00 sec)
mysql> SELECT * FROM courses;#查询courses表
+-----+-----------+
| CID | Couse |
+-----+-----------+
| 1 | physics |
| 2 | english |
| 3 | chemistry |
| 4 | maths |
+-----+-----------+
4 rows in set (0.00 sec)
mysql> SELECT Name,Couse FROM student,courses WHERE student.CID=courses.CID; #查询student表和courses表中CID相同的Name和Couse字段内容
+------------+---------+
| Name | Couse |
+------------+---------+
| Li Lianjie | physics |
| Cheng Long | english |
+------------+---------+
2 rows in set (0.00 sec)
mysql> DELETE FROM student WHERE SID > 5; 删除SID大于5的行。
Query OK, 5 rows affected (0.01 sec)
mysql> ALTER TABLE courses ENGINE=Innodb; #修改courses表的引擎为Innodb;
Query OK, 4 rows affected (0.03 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> ALTER TABLE student MODIFY CID TINYINT UNSIGNED NOT NULL;#修改student表中CID字段的修饰（MODIFY）。
Query OK, 4 rows affected (0.02 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> DESC courses;
+-------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+----------------+
| CID | tinyint(3) unsigned | NO | PRI | NULL | auto_increment |
| Couse | varchar(50) | NO | | NULL | |
+-------+---------------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
mysql> DESC student;
+-------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+----------------+
| SID | int(10) unsigned | NO | PRI | NULL | auto_increment |
| Name | varchar(30) | YES | | NULL | |
| CID | tinyint(3) unsigned | NO | | NULL | |
+-------+---------------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)
mysql> ALTER TABLE student ADD FOREIGN KEY foreign_cid (CID) REFERENCES courses (CID);
为student表的CID字段增加一个外键foreign_cid关联courses表的CID字段。
Query OK, 4 rows affected (0.03 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> SHOW INDEXES FROM student; 查看student表的索引
+---------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| student | 0 | PRIMARY | 1 | SID | A | 2 | NULL | NULL | | BTREE | | |
| student | 1 | foreign_cid | 1 | CID | A | 2 | NULL | NULL | | BTREE | | |
+---------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
2 rows in set (0.00 sec)
mysql> INSERT INTO student (Name,CID) VALUES ('Guo Xiang',5);
ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails (`students`.`student`, CONSTRAINT `student_ibfk_1` FOREIGN KEY (`CID`) REFERENCES `courses` (`CID`)) #提示报错，由于CID外键索引courses表中CID没有5，所以无法增加。
mysql> ALTER TABLE student AUTO_INCREMENT=5;#设定student表下一条数据的自动增长主键SID
从5开始增长。
Query OK, 4 rows affected (0.05 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM student;#查询表的内容
+-----+-------------+-----+
| SID | Name | CID |
+-----+-------------+-----+
| 1 | Li Lianjie | 1 |
| 2 | Cheng Long | 2 |
| 3 | Xiao Longnv | 3 |
| 4 | Yang Guo | 4 |
+-----+-------------+-----+
4 rows in set (0.00 sec)
mysql> INSERT INTO student (Name,CID) VALUES ('Guo Xiang',3);#插入一条数据，SID主键由于上面设置从5开始增长，所以刚插入的数据是从5开始；
Query OK, 1 row affected (0.00 sec)
mysql> SELECT * FROM student;
+-----+-------------+-----+
| SID | Name | CID |
+-----+-------------+-----+
| 1 | Li Lianjie | 1 |
| 2 | Cheng Long | 2 |
| 3 | Xiao Longnv | 3 |
| 4 | Yang Guo | 4 |
| 5 | Guo Xiang | 3 |
+-----+-------------+-----+
5 rows in set (0.00 sec)
mysql> INSERT INTO student (Name,CID) VALUES ('Qiao Feng',2);插入数据
Query OK, 1 row affected (0.00 sec)
mysql> SELECT * FROM student;
+-----+-------------+-----+
| SID | Name | CID |
+-----+-------------+-----+
| 1 | Li Lianjie | 1 |
| 2 | Cheng Long | 2 |
| 3 | Xiao Longnv | 3 |
| 4 | Yang Guo | 4 |
| 5 | Guo Xiang | 3 |
| 6 | Qiao Feng | 2 |
+-----+-------------+-----+
6 rows in set (0.00 sec)
mysql> DELETE FROM student WHERE SID >2 AND SID <5; #删除2<SID<5的行
Query OK, 2 rows affected (0.00 sec)
mysql> SELECT * FROM student;
+-----+------------+-----+
| SID | Name | CID |
+-----+------------+-----+
| 1 | Li Lianjie | 1 |
| 2 | Cheng Long | 2 |
| 5 | Guo Xiang | 3 |
| 6 | Qiao Feng | 2 |
+-----+------------+-----+
4 rows in set (0.00 sec)
mysql> DELETE FROM student WHERE SID in (5,6); #删除SID为5和6的行
Query OK, 2 rows affected (0.00 sec)
mysql> SELECT * FROM student;
+-----+------------+-----+
| SID | Name | CID |
+-----+------------+-----+
| 1 | Li Lianjie | 1 |
| 2 | Cheng Long | 2 |
+-----+------------+-----+
2 rows in set (0.00 sec)
mysql> ALTER TABLE student AUTO_INCREMENT=3; #设定student表下一条数据的自动增长主键
SID从3开始增长。
Query OK, 2 rows affected (0.07 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> INSERT INTO student (Name,CID) VALUES ('Yang Guo',3),('Guo Jing',4);#插入2条数据
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM student;
+-----+------------+-----+
| SID | Name | CID |
+-----+------------+-----+
| 1 | Li Lianjie | 1 |
| 2 | Cheng Long | 2 |
| 3 | Yang Guo | 3 |
| 4 | Guo Jing | 4 |
+-----+------------+-----+
4 rows in set (0.00 sec)
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