mysql 增删改查最基本用法小结
2024-10-10 20:46:19
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 )类型 非空 唯一值 school ) 非空 默认值chengdu college
代码如下:
1.建立数据库
mysql> CREATE DATABASE students; Query OK, 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 , ) NOT NULL UNIQUE KEY , ) DEFAULT 'chengdu_collage' , -> PRIMARY KEY(id) -> ); Query OK, rows affected (0.09 sec)
4.查看表结构
mysql> DESC class1; +--------+----------------------+------+-----+-----------------+----------------+ | Field | Type | Null | Key | Default | Extra | +--------+----------------------+------+-----+-----------------+----------------+ ) unsigned | NO | PRI | NULL | auto_increment | ) | NO | UNI | NULL | | ) | YES | | chengdu_collage | | +--------+----------------------+------+-----+-----------------+----------------+ rows in set (0.00 sec)
1.插入(INSERT)
.INSERT INTO tb_name [(col_name...)] {VALUES|VALUE}({expr | DEFAULT},....),(...)... 例子: mysql> INSERT INTO class1 (name) VALUES ('john'); Query OK, row affected (0.01 sec) mysql> INSERT INTO class1 VALUES (DEFAULT,'jobs','chengdu_agricultural_college'); Query OK, row affected (0.01 sec) .INSERT INTO tb_name SET col_name = {expr | DEFAULT},... 例子: mysql> INSERT INTO class1 SET name='tom'; Query OK, row affected (0.02 sec) mysql> INSERT INTO class1 SET name='lues',school='chengdu_agricultural_college'; Query OK, row affected (0.01 sec)
2.修改(UPDATE)
.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, row affected (0.07 sec) Rows matched: Changed: Warnings:
3.删除(DELETE)
.DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM tbl_name [WHERE where_condition] 例子: mysql> DELETE FROM class1 WHERE name='lues2'; Query OK, row affected (0.01 sec)
4.查询(SELECT)
.简单查询 mysql> SELECT * FROM class1; +----+------+------------------------------+ | id | name | school | +----+------+------------------------------+ | john | chengdu_collage | | jobs | chengdu_agricultural_college | | tom | chengdu_collage | +----+------+------------------------------+ rows in set (0.00 sec) .简单的条件查询 mysql; +----+------+------------------------------+ | id | name | school | +----+------+------------------------------+ | jobs | chengdu_agricultural_college | | tom | chengdu_collage | +----+------+------------------------------+ rows in set (0.00 sec) .简单的分组查询 mysql> SELECT * FROM class1 GROUP BY school DESC; +----+------+------------------------------+ | id | name | school | +----+------+------------------------------+ | john | chengdu_collage | | jobs | chengdu_agricultural_college | +----+------+------------------------------+ rows in set (0.00 sec) .简单的排序查询 mysql> SELECT * FROM class1 ORDER BY id DESC; +----+------+------------------------------+ | id | name | school | +----+------+------------------------------+ | tom | chengdu_collage | | jobs | chengdu_agricultural_college | | john | chengdu_collage | +----+------+------------------------------+ rows in set (0.00 sec)
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