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mysql 增删改查最基本用法小结
阅读量:7199 次
发布时间:2019-06-29

本文共 4307 字,大约阅读时间需要 14 分钟。

目录:

  1.新建数据库

  2.新建数据表
  3.查看表结构
  4.增删改查

 

 建立一个数据库students

 建立一块数据表class1
  内容包括:

  id 主键 自动编号 无符号位 SMALLINT类型  name VARCHAR(30)类型 非空 唯一值  school VARCHAR(30) 非空 默认值chengdu college

 

代码如下:
1.建立数据库

mysql> CREATE DATABASE students;        Query OK, 1 row affected (0.07 sec)

2.进入数据库

mysql> USE students;        Database changed

 

 

3.新建表

mysql> CREATE TABLE class1 (        -> id SMALLINT UNSIGNED AUTO_INCREMENT ,        -> name VARCHAR(30) NOT NULL UNIQUE KEY ,        -> school VARCHAR(30) DEFAULT 'chengdu_collage' ,        -> PRIMARY KEY(id)        -> );        Query OK, 0 rows affected (0.09 sec)

 

4.查看表结构

mysql> DESC class1;        +--------+----------------------+------+-----+-----------------+----------------+        | Field  | Type                 | Null | Key | Default         | Extra          |        +--------+----------------------+------+-----+-----------------+----------------+        | id     | smallint(5) unsigned | NO   | PRI | NULL            | auto_increment |        | name   | varchar(30)          | NO   | UNI | NULL            |                |        | school | varchar(30)          | YES  |     | chengdu_collage |                |        +--------+----------------------+------+-----+-----------------+----------------+        3 rows in set (0.00 sec)

 

1.插入(INSERT)

1.INSERT INTO tb_name [(col_name...)] {
VALUES|VALUE}({expr | DEFAULT},....),(...)... 例子: mysql> INSERT INTO class1 (name) VALUES ('john'); Query OK, 1 row affected (0.01 sec) mysql> INSERT INTO class1 VALUES (DEFAULT,'jobs','chengdu_agricultural_college'); Query OK, 1 row affected (0.01 sec) 2.INSERT INTO tb_name SET col_name = {expr | DEFAULT},... 例子: mysql> INSERT INTO class1 SET name='tom'; Query OK, 1 row affected (0.02 sec) mysql> INSERT INTO class1 SET name='lues',school='chengdu_agricultural_college'; Query OK, 1 row affected (0.01 sec)

 

2.修改(UPDATE)

1.UPDATE [LOW_PRIORITY] [IGNORE] table_reference    SET col_name1={expr1|DEFAULT} [, col_name2={expr2|DEFAULT}] ...    例子:        mysql> UPDATE class1         -> SET name='lues2' WHERE name='lues';        Query OK, 1 row affected (0.07 sec)        Rows matched: 1  Changed: 1  Warnings: 0

 

3.删除(DELETE)

1.DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM tbl_name      [WHERE where_condition]          例子:        mysql> DELETE FROM class1 WHERE name='lues2';        Query OK, 1 row affected (0.01 sec)

 

4.查询(SELECT)

1.简单查询        mysql> SELECT * FROM class1;        +----+------+------------------------------+        | id | name | school                       |        +----+------+------------------------------+        |  1 | john | chengdu_collage              |        |  2 | jobs | chengdu_agricultural_college |        |  3 | tom  | chengdu_collage              |        +----+------+------------------------------+        3 rows in set (0.00 sec)            2.简单的条件查询        mysql> SELECT * FROM class1 WHERE id > 1;        +----+------+------------------------------+        | id | name | school                       |        +----+------+------------------------------+        |  2 | jobs | chengdu_agricultural_college |        |  3 | tom  | chengdu_collage              |        +----+------+------------------------------+        2 rows in set (0.00 sec)            3.简单的分组查询        mysql> SELECT * FROM class1 GROUP BY school DESC;        +----+------+------------------------------+        | id | name | school                       |        +----+------+------------------------------+        |  1 | john | chengdu_collage              |        |  2 | jobs | chengdu_agricultural_college |        +----+------+------------------------------+        2 rows in set (0.00 sec)            4.简单的排序查询        mysql> SELECT * FROM class1 ORDER BY id DESC;        +----+------+------------------------------+        | id | name | school                       |        +----+------+------------------------------+        |  3 | tom  | chengdu_collage              |        |  2 | jobs | chengdu_agricultural_college |        |  1 | john | chengdu_collage              |        +----+------+------------------------------+        3 rows in set (0.00 sec)

 

转载于:https://www.cnblogs.com/wang-li/p/5914287.html

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