MySQL—常用SQL语句整理总结

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引言

  记录并整理常用的SQL语句使用笔记。

创建数据库和表

创建库(CREATE DATABASE)

CREATE DATABASE database_name

进入库(USE)

USE database_name

查看表(SHOW)

SHOW TABLES;
SHOW TABLES FROM database_name;

创建表(CREATE TABLE)

CREATE TABLE table_name (column1_name INT, column2_name VARCHAR(50), column3_name VARCHAR(50));

mysql> CREATE TABLE students
    -> (id INT,
    -> name VARCHAR(32),
    -> age INT,
    -> birthday DATE,
    -> class_id INT(11));
Query OK, 0 rows affected (0.34 sec)

mysql> CREATE TABLE class
    -> (class_id INT AUTO_INCREMENT PRIMARY KEY,
    -> class_name VARCHAR(32),
    -> grade_id INT,
    -> class_teacher VARCHAR(32));
Query OK, 0 rows affected (0.33 sec)

描述表(DESC)

DESCRIBE table_name;

mysql> DESC students;
+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id       | int(11)     | YES  |     | NULL    |       |
| name     | varchar(32) | YES  |     | NULL    |       |
| age      | int(11)     | YES  |     | NULL    |       |
| birthday | date        | YES  |     | NULL    |       |
| class_id | int(11)     | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

mysql> DESC class;
+---------------+-------------+------+-----+---------+----------------+
| Field         | Type        | Null | Key | Default | Extra          |
+---------------+-------------+------+-----+---------+----------------+
| class_id      | int(11)     | NO   | PRI | NULL    | auto_increment |
| class_name    | varchar(32) | YES  |     | NULL    |                |
| grade_id      | int(11)     | YES  |     | NULL    |                |
| class_teacher | varchar(32) | YES  |     | NULL    |                |
+---------------+-------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

修改列(ALTER TABLE)

修改列(CHANGE COLUMN)

ALTER TABLE table_name CHANGE COLUMN old_col_name new_col_name INT AUTO_INCREMENT PRIMARY KEY

mysql> ALTER TABLE students
    -> CHANGE COLUMN id id INT AUTO_INCREMENT PRIMARY KEY;
Query OK, 0 rows affected (1.10 sec)
Records: 0  Duplicates: 0  Warnings: 0


mysql> DESC students;
+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| id         | int(11)      | NO   | PRI | NULL    | auto_increment |
| name       | varchar(32)  | YES  |     | NULL    |                |
| age        | int(11)      | YES  |     | NULL    |                |
| birthday   | date         | YES  |     | NULL    |                |
| class_id   | int(11)      | YES  |     | NULL    |                |
+------------+--------------+------+-----+---------+----------------+
5 rows in set (0.00 sec)

增加列(ADD COLUMN)

ALTER TABLE table_name ADD COLUMN new_col1_name TEXT , ADD COLUMN new_col2_name VARCHAR(255), ... ...

mysql> ALTER TABLE students
    -> ADD COLUMN student_id INT,
    -> ADD COLUMN address VARCHAR(255);
Query OK, 0 rows affected (1.10 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC students;
+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| id         | int(11)      | NO   | PRI | NULL    | auto_increment |
| name       | varchar(32)  | YES  |     | NULL    |                |
| age        | int(11)      | YES  |     | NULL    |                |
| birthday   | date         | YES  |     | NULL    |                |
| class_id   | int(11)      | YES  |     | NULL    |                |
| student_id | int(11)      | YES  |     | NULL    |                |
| address    | varchar(255) | YES  |     | NULL    |                |
+------------+--------------+------+-----+---------+----------------+
7 rows in set (0.00 sec)

删除列

ALTER TABLE table_name DROP COLUMN col1_name, DROP COLUMN col2_name

mysql> ALTER TABLE students
    -> DROP COLUMN age;
Query OK, 0 rows affected (3.73 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC students;
+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| id         | int(11)      | NO   | PRI | NULL    | auto_increment |
| name       | varchar(32)  | YES  |     | NULL    |                |
| birthday   | date         | YES  |     | NULL    |                |
| class_id   | int(11)      | YES  |     | NULL    |                |
| student_id | int(11)      | YES  |     | NULL    |                |
| address    | varchar(255) | YES  |     | NULL    |                |
+------------+--------------+------+-----+---------+----------------+
6 rows in set (0.00 sec)

插入数据(INSERT INTO)

INSERT INTO table_name (col1_name, col2_name, col4_name) VALUES (col1_value, col2_value, col4_value);

mysql> INSERT INTO students 
	-> (name, birthday, address, class_id, student_id) 
	-> VALUES('xiaoming', '1996-07-01', '江苏省苏州市相城区', 3, 080301);
	
mysql> INSERT INTO students 
    -> (name, birthday, address, class_id, student_id)
    -> VALUES('xiaohong', '1995-09-05', '安徽省马鞍山市', 3, 080310);
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO students
    -> (id, name, birthday, address, class_id, student_id)
    -> VALUES(5, '秦明', '1996-03-03', '江苏省南京市', 2, 080205);
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO students
    -> (id, name, birthday, address, class_id, student_id)
    -> VALUES(4, '黄盖', '1996-05-21', '江苏省无锡市', 1, 080102);
Query OK, 1 row affected (0.00 sec)

查看最后记录(LAST_INSERT_ID())

SELECT LAST_INSERT_ID();，通过LAST_INSERT_ID()函数可以从表中取出刚输入的记录的标识码。

 SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                3 |
+------------------+
1 row in set (0.00 sec)

修改数据

修改某些列(UPDATE SET)

UPDATE table_name SET col1_name = 'new_value' WHRE col2_name = 'xxx';，若需要修改多列，则用逗号分开列表即可。

将三班的年纪号改为1，老师改为吴老师

mysql> INSERT INTO class VALUES(1, '一班', '1', '王老师');
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO class VALUES(2, '二班', '1', '徐老师');
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO class
    -> (class_id, class_name, grade_id, class_teacher)
    -> VALUES (3, '三班', 3, '陈老师');
Query OK, 1 row affected (0.01 sec)

mysql> SELECT * FROM class;
+----------+------------+----------+---------------+
| class_id | class_name | grade_id | class_teacher |
+----------+------------+----------+---------------+
|        1 | 一班       |        1 | 王老师        |
|        2 | 二班       |        1 | 徐老师        |
|        3 | 三班       |        3 | 陈老师        |
+----------+------------+----------+---------------+
3 rows in set (0.00 sec)

mysql> UPDATE class SET grade_id = 1, class_teacher = '吴老师' WHERE class_id = 3;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> SELECT * FROM class;
+----------+------------+----------+---------------+
| class_id | class_name | grade_id | class_teacher |
+----------+------------+----------+---------------+
|        1 | 一班       |        1 | 王老师        |
|        2 | 二班       |        1 | 徐老师        |
|        3 | 三班       |        1 | 吴老师        |
+----------+------------+----------+---------------+
3 rows in set (0.01 sec)

替换数据

REPLACE INTO类似于INSERT INTO语句，但是该语句可以替换已存在的值，若某些值唯一之后。

1. 使用UNIQUE将字段置为唯一性

mysql> ALTER TABLE students 
    -> CHANGE COLUMN student_id student_id INT UNIQUE;
Query OK, 0 rows affected (0.44 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC students;
+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| id         | int(11)      | NO   | PRI | NULL    | auto_increment |
| name       | varchar(32)  | YES  |     | NULL    |                |
| birthday   | date         | YES  |     | NULL    |                |
| class_id   | int(11)      | YES  |     | NULL    |                |
| student_id | int(11)      | YES  | UNI | NULL    |                |
| address    | varchar(255) | YES  |     | NULL    |                |
+------------+--------------+------+-----+---------+----------------+
6 rows in set (0.00 sec)

2. 替换数据

mysql> SELECT * FROM students;
+----+----------+------------+----------+------------+-----------------------------+
| id | name     | birthday   | class_id | student_id | address                     |
+----+----------+------------+----------+------------+-----------------------------+
|  1 | xiaoming | 1996-07-01 |        3 |      80301 | 江苏省苏州市相城区          |
|  3 | xiaohong | 1995-09-05 |        3 |      80310 | 安徽省马鞍山市              |
|  4 | 黄盖     | 1996-05-21 |        1 |      80102 | 江苏省无锡市                |
|  5 | 秦明     | 1996-03-03 |        2 |      80205 | 江苏省南京市                |
+----+----------+------------+----------+------------+-----------------------------+
4 rows in set (0.01 sec)

mysql> SELECT * FROM students WHERE id = 1;
+----+----------+------------+----------+------------+-----------------------------+
| id | name     | birthday   | class_id | student_id | address                     |
+----+----------+------------+----------+------------+-----------------------------+
|  1 | xiaoming | 1996-07-01 |        3 |      80301 | 江苏省苏州市相城区          |
+----+----------+------------+----------+------------+-----------------------------+
1 row in set (0.00 sec)

mysql> REPLACE INTO students
    -> (name, birthday, class_id, student_id, address)
    -> VALUES('小王', '1997-01-02', 3, 80303, '江苏省苏州市'), 
    -> ('xiaoming', '1996-07-01', 3, 80301, '江苏省苏州市相城区');
Query OK, 3 rows affected (0.05 sec)
Records: 2  Duplicates: 1  Warnings: 0

mysql> SELECT * FROM students;
+----+----------+------------+----------+------------+-----------------------------+
| id | name     | birthday   | class_id | student_id | address                     |
+----+----------+------------+----------+------------+-----------------------------+
|  3 | xiaohong | 1995-09-05 |        3 |      80310 | 安徽省马鞍山市              |
|  4 | 黄盖     | 1996-05-21 |        1 |      80102 | 江苏省无锡市                |
|  5 | 秦明     | 1996-03-03 |        2 |      80205 | 江苏省南京市                |
|  6 | 小王     | 1997-01-02 |        3 |      80303 | 江苏省苏州市                |
|  7 | xiaoming | 1996-07-01 |        3 |      80301 | 江苏省苏州市相城区          |
+----+----------+------------+----------+------------+-----------------------------+
5 rows in set (0.00 sec)

mysql>  REPLACE INTO students
    -> (id, name, birthday, class_id, student_id, address)
    -> VALUES(1, 'xiaoming', '1996-07-01', 3, 80301, '江苏省苏州市相城区');
Query OK, 2 rows affected (0.00 sec)

mysql> SELECT * FROM students;
+----+----------+------------+----------+------------+-----------------------------+
| id | name     | birthday   | class_id | student_id | address                     |
+----+----------+------------+----------+------------+-----------------------------+
|  1 | xiaoming | 1996-07-01 |        3 |      80301 | 江苏省苏州市相城区          |
|  3 | xiaohong | 1995-09-05 |        3 |      80310 | 安徽省马鞍山市              |
|  4 | 黄盖     | 1996-05-21 |        1 |      80102 | 江苏省无锡市                |
|  5 | 秦明     | 1996-03-03 |        2 |      80205 | 江苏省南京市                |
|  6 | 小王     | 1997-01-02 |        3 |      80303 | 江苏省苏州市                |
+----+----------+------------+----------+------------+-----------------------------+
5 rows in set (0.00 sec)

mysql>  REPLACE INTO students
    -> (name, birthday, class_id, student_id, address)
    -> VALUES('huangwen', '1995-02-04', 3, 80301, '江苏省盐城市');
Query OK, 2 rows affected (0.00 sec)

mysql> SELECT * FROM students;
+----+----------+------------+----------+------------+-----------------------+
| id | name     | birthday   | class_id | student_id | address               |
+----+----------+------------+----------+------------+-----------------------+
|  3 | xiaohong | 1995-09-05 |        3 |      80310 | 安徽省马鞍山市        |
|  4 | 黄盖     | 1996-05-21 |        1 |      80102 | 江苏省无锡市          |
|  5 | 秦明     | 1996-03-03 |        2 |      80205 | 江苏省南京市          |
|  6 | 小王     | 1997-01-02 |        3 |      80303 | 江苏省苏州市          |
|  8 | huangwen | 1995-02-04 |        3 |      80301 | 江苏省盐城市          |
+----+----------+------------+----------+------------+-----------------------+
5 rows in set (0.00 sec)

删除数据(DELETE FROM)

子查询删除

mysql> SELECT * FROM class;
+----------+------------+----------+---------------+
| class_id | class_name | grade_id | class_teacher |
+----------+------------+----------+---------------+
|        1 | 一班       |        1 | 王老师        |
|        2 | 二班       |        1 | 徐老师        |
|        3 | 三班       |        1 | 吴老师        |
+----------+------------+----------+---------------+
3 rows in set (0.00 sec)

mysql> SELECT * FROM students;
+----+----------+------------+----------+------------+-----------------------+
| id | name     | birthday   | class_id | student_id | address               |
+----+----------+------------+----------+------------+-----------------------+
|  3 | xiaohong | 1995-09-05 |        3 |      80310 | 安徽省马鞍山市        |
|  4 | 黄盖     | 1996-05-21 |        1 |      80102 | 江苏省无锡市          |
|  5 | 秦明     | 1996-03-03 |        2 |      80205 | 江苏省南京市          |
|  6 | 小王     | 1997-01-02 |        3 |      80303 | 江苏省苏州市          |
|  8 | huangwen | 1995-02-04 |        3 |      80301 | 江苏省盐城市          |
+----+----------+------------+----------+------------+-----------------------+
5 rows in set (0.00 sec)

mysql> DELETE FROM students
    -> WHERE class_id = 
    -> (SELECT c.class_id FROM class c WHERE class_teacher = '徐老师');
Query OK, 1 row affected (0.00 sec)

mysql> SELECT * FROM students;
+----+----------+------------+----------+------------+-----------------------+
| id | name     | birthday   | class_id | student_id | address               |
+----+----------+------------+----------+------------+-----------------------+
|  3 | xiaohong | 1995-09-05 |        3 |      80310 | 安徽省马鞍山市        |
|  4 | 黄盖     | 1996-05-21 |        1 |      80102 | 江苏省无锡市          |
|  6 | 小王     | 1997-01-02 |        3 |      80303 | 江苏省苏州市          |
|  8 | huangwen | 1995-02-04 |        3 |      80301 | 江苏省盐城市          |
+----+----------+------------+----------+------------+-----------------------+
4 rows in set (0.00 sec)

查询设置变量删除

mysql> SET @class_id = 
    -> (SELECT class_id FROM class WHERE class_teacher = '徐老师');
Query OK, 0 rows affected (0.00 sec)

mysql> DELETE FROM students
    -> WHERE class_id = @class_id;
Query OK, 0 rows affected (0.00 sec)

选择数据(SELECT)

全列查询(SELECT *)

SELECT * FROM table_name

mysql> SELECT * FROM students;
+----+----------+-----------+----------+------------+-----------------------------+
| id | name     | birthday   | class_id | student_id | address                     |
+----+----------+------+------------+----------+------------+-----------------------------+
|  1 | xiaoming | 1996-07-01 |        3 |      80301 | 江苏省苏州市相城区          |
|  3 | xiaohong |1995-09-05 |        3 |      80310 | 安徽省马鞍山市              |
|  4 | 黄盖     | 1996-05-21 |        1 |      80102 | 江苏省无锡市                |
|  5 | 秦明     | 1996-03-03 |        2 |      80205 | 江苏省南京市                |
+----+----------+------+------------+----------+------------+-----------------------------+
4 rows in set (0.00 sec)

选择列查询(SELECT col)

SELECT col1_name, col4_name FROM table_name WHERE col3_name = 'valuexxx';

mysql> SELECT name, student_id FROM students WHERE class_id = 3;
+----------+------------+
| name     | student_id |
+----------+------------+
| xiaoming |      80301 |
| xiaohong |      80310 |
+----------+------------+
2 rows in set (0.00 sec)

表关联查询（JOIN USING）

JOIN ... USING，USING用于两个表相同列值相同查询。并使用CONCAT(str1, str2, ...)进行字符串拼接

mysql> SELECT name, birthday, address, 
    -> CONCAT(grade_id, '年级', class_name) AS class_info
    -> FROM students 
    -> JOIN class USING(class_id)
    -> WHERE class_teacher = '吴老师';
+----------+------------+-----------------------------+---------------+
| name     | birthday   | address                     | class_info    |
+----------+------------+-----------------------------+---------------+
| xiaoming | 1996-07-01 | 江苏省苏州市相城区          | 1年级三班     |
| xiaohong | 1995-09-05 | 安徽省马鞍山市              | 1年级三班     |
+----------+------------+-----------------------------+---------------+
2 rows in set (0.00 sec)

排序(ORDER BY)

升序

默认使用升序

mysql> SELECT * FROM students ORDER BY birthday;
+----+----------+------------+----------+------------+-----------------------------+
| id | name     | birthday   | class_id | student_id | address                     |
+----+----------+------------+----------+------------+-----------------------------+
|  3 | xiaohong | 1995-09-05 |        3 |      80310 | 安徽省马鞍山市              |
|  5 | 秦明     | 1996-03-03 |        2 |      80205 | 江苏省南京市                |
|  4 | 黄盖     | 1996-05-21 |        1 |      80102 | 江苏省无锡市                |
|  1 | xiaoming | 1996-07-01 |        3 |      80301 | 江苏省苏州市相城区          |
+----+----------+------------+----------+------------+-----------------------------+
4 rows in set (0.00 sec)

降序

使用DESC进行降序处理

mysql> SELECT * FROM students ORDER BY birthday DESC;
+----+----------+------------+----------+------------+-----------------------------+
| id | name     | birthday   | class_id | student_id | address                     |
+----+----------+------------+----------+------------+-----------------------------+
|  1 | xiaoming | 1996-07-01 |        3 |      80301 | 江苏省苏州市相城区          |
|  4 | 黄盖     | 1996-05-21 |        1 |      80102 | 江苏省无锡市                |
|  5 | 秦明     | 1996-03-03 |        2 |      80205 | 江苏省南京市                |
|  3 | xiaohong | 1995-09-05 |        3 |      80310 | 安徽省马鞍山市              |
+----+----------+------------+----------+------------+-----------------------------+
4 rows in set (0.00 sec)

限制(LIMIT)

限制个数

LIMIT n 限制n个展示

mysql> SELECT * FROM students LIMIT 2;
+----+----------+------------+----------+------------+-----------------------------+
| id | name     | birthday   | class_id | student_id | address                     |
+----+----------+------------+----------+------------+-----------------------------+
|  1 | xiaoming | 1996-07-01 |        3 |      80301 | 江苏省苏州市相城区          |
|  3 | xiaohong | 1995-09-05 |        3 |      80310 | 安徽省马鞍山市              |
+----+----------+------------+----------+------------+-----------------------------+
2 rows in set (0.01 sec)

跳过限制个数

LIMIT(m, n)，跳过m个，展示后面n个。

mysql> SELECT * FROM students LIMIT 2, 1;
+----+--------+------------+----------+------------+--------------------+
| id | name   | birthday   | class_id | student_id | address            |
+----+--------+------------+----------+------------+--------------------+
|  4 | 黄盖   | 1996-05-21 |        1 |      80102 | 江苏省无锡市       |
+----+--------+------------+----------+------------+--------------------+
1 row in set (0.00 sec)

模糊查询

使用LIKE和%进行模糊匹配

mysql> SELECT `name`, birthday, address
    -> FROM students
    -> WHERE address LIKE '%江苏%';
+----------+------------+--------------------+
| name     | birthday   | address            |
+----------+------------+--------------------+
| 黄盖     | 1996-05-21 | 江苏省无锡市       |
| 小王     | 1997-01-02 | 江苏省苏州市       |
| huangwen | 1995-02-04 | 江苏省盐城市       |
+----------+------------+--------------------+
3 rows in set (0.00 sec)

交集并集查询

1. 使用AND进行交集查询

mysql> SELECT `name`, birthday, address
    -> FROM students 
    -> WHERE address LIKE '%江苏%' AND class_id = 1;
+--------+------------+--------------------+
| name   | birthday   | address            |
+--------+------------+--------------------+
| 黄盖   | 1996-05-21 | 江苏省无锡市       |
+--------+------------+--------------------+
1 row in set (0.00 sec)

2. 使用OR进行并集查询

mysql> SELECT `name`, birthday, address
    -> FROM students 
    -> WHERE `name` LIKE '%xiao%' OR `name` LIKE '%小%';
+----------+------------+-----------------------+
| name     | birthday   | address               |
+----------+------------+-----------------------+
| xiaohong | 1995-09-05 | 安徽省马鞍山市        |
| 小王     | 1997-01-02 | 江苏省苏州市          |
+----------+------------+-----------------------+
2 rows in set (0.00 sec)

分析处理数据

统计个数(COUNT)

COUNT(*)函数

mysql> SELECT COUNT(*)
    -> FROM students
    -> JOIN class USING (class_id)
    -> WHERE class_name = '三班';
+----------+
| COUNT(*) |
+----------+
|        2 |
+----------+
1 row in set (0.00 sec)

求和函数(SUM)

SUM(col_name)

mysql> SELECT SUM(grade_id) AS 'grade_sum'
    -> FROM class
    -> JOIN students USING (class_id);
+-----------+
| grade_sum |
+-----------+
|         4 |
+-----------+
1 row in set (0.00 sec)

日期处理

函数：月MONTHNAME(col_name), 日DAYOFMONTH(col_name)，年YEAR(col_name)

mysql> SELECT CONCAT(MONTHNAME(birthday), ' ',
    -> DAYOFMONTH(birthday), ',',
    -> YEAR(birthday)) AS student_birthday
    -> FROM students
    -> WHERE `name` = 'xiaoming';
+------------------+
| student_birthday |
+------------------+
| July 1,1996      |
+------------------+
1 row in set (0.00 sec)

函数DATE_FORMAT(col_name, "%M %d, %Y")

mysql> SELECT DATE_FORMAT(birthday, "%M %d, %Y")
    -> AS 'student_birth_date' 
    -> FROM students
    -> WHERE `name` = 'xiaohong';
+--------------------+
| student_birth_date |
+--------------------+
| September 05, 1995 |
+--------------------+
1 row in set (0.00 sec)

批量导入数据

1. mysql文件目录

mysql> SHOW VARIABLES LIKE '%secure_file_priv%';
+------------------+-----------------------+
| Variable_name    | Value                 |
+------------------+-----------------------+
| secure_file_priv | /var/lib/mysql-files/ |
+------------------+-----------------------+
1 row in set (0.00 sec)

2. 创建txt文件

[linux01@t1 /var/lib/mysql-files] touch sql_data.txt
[linux01@t1 /var/lib/mysql-files] vim sql_data.txt
[linux01@t1 /var/lib/mysql-files]#  cat sql_data.txt 
name     | birthday   | class_id | student_id |address|
xiaow| 1995-09-05|3|80310|anhui|
xiaoh| 1996-05-01|2|80209|zhejiang|

3. 导入

mysql> LOAD DATA INFILE '/var/lib/mysql-files/sql_data.txt' 
    -> REPLACE INTO TABLE students 
    -> FIELDS TERMINATED BY '|' LINES TERMINATED BY '
'  IGNORE 1 LINES
    -> (`name`, birthday, class_id, student_id, address);
Query OK, 2 rows affected (0.01 sec)
Records: 2  Deleted: 0  Skipped: 0  Warnings: 0

mysql> SELECT * FROM students;
+------+-------+------------+----------+------------+----------+
| id   | name  | birthday   | class_id | student_id | address  |
+------+-------+------------+----------+------------+----------+
| 1| xiaow | 1995-09-05 |        3 |      80310 | anhui    |
| 2 | xiaoh | 1996-05-01 |        2 |      80209 | zhejiang |
+------+-------+------------+----------+------------+----------+
2 rows in set (0.00 sec)