免费书画网站模板,哈尔滨信息网,注册国际贸易公司需要多少钱,网站为什么做301登陆数据库#xff1a;mysql -u用户名 -p密码 -P端口 -h数据库地址修改mysql提示符#xff1a;(仅本次连接有效)方法一#xff1a;执行mysql -uroot -proot -prompt \h结果为#xff1a;localhost方法二#xff1a;进入mysql后#xff0c;执行PR…登陆数据库mysql -u用户名 -p密码 -P端口 -h数据库地址修改mysql提示符(仅本次连接有效)方法一执行mysql -uroot -proot -prompt \h结果为localhost方法二进入mysql后执行PROMPT \u\h \d结果为rootlocalhost(数据库名)参数说明\D完整日期\d当前数据库\h服务器名称(域名/IP)\u系统当前用户库级操作SELECT USER();//显示当前用户SELECT DATABASE();//显示打开的数据库//创建数据库//CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] db_name [DEFAULT] CHARACTER SET [] charset_name;CREATE DATABASE hehe;//查看已有的数据库信息(比如编码等)SHOW CREATE DATABASE hehe;//显示数据库//SHOW {DATABASES | SCHEMA} [LIKE Ppattern | WHERE expr]SHOW DATABASES;//修改数据库(比如编码等)//ALTER {DATABASE | SCHEMA} [IF NOT EXISTS] db_name [DEFAULT] CHARACTER SET [] charset_name;//删除数据库//DROP {DATABASE | SCHEMA} [IF NOT EXISTS] db_nameDROP DATABASE hehe;表级操作//创建表//列名 数据类型 [数值型是否有符号] [是否可NULL] [默认值] [唯一约束] [自动递增1开始] [主键一张表只能有一个]//列名 数据类型 [UNSGINED] [NULL | NOT NULL] [DEFAULT value] [UNIQUE KEY] [AUTO_INCREMENT] [PREMARY KEY]CREATE TABLE table_name(username varchar(20),number int(11) unsgined,sex ENUM(1,2,3) DEFAULT 3,);//查看表SELECT TABLES [FROM 数据库名];//查看表结构SHOW COLUMNS FROM table_name;//修改表名方法一ALTER TABLE table_name RENAME new_name方法二RENAME TABLE table_name TO new_name [, table_name2 TO new_name2,...]//添加列ALTER TABLE table_name ADD password varchar(20) NOT NULL AFTER {username | FIRST | LAST};//删除列并增加ALTER TABLE table_name DROP password, DROP username, ADD id;//修改列定义ALTER TABLE table_name MODIFY username varchar(50) NOT NULL;//修改列名和定义ALTER TBALE table_name CHANGE old_col_name new_col_name [定义] [FIRST | AFTER col_name]//列操作总结ALTER TABLE table_name [操作],[操作]...增、删、改、查增//INSERT [INTO] table_name [(列名1,列名2,...)] VALUE(第一条),(第二条),...;INSERT table_name (username, password, age) VALUE (zhangsan, 123456, 12),(lisi, 123456, 18);//INSERT [INTO] table_name SET usernamewangwu,password123456;只能插入单条//INSERT [INTO] table_name [(列名1,列名2,...)] SELECT...删//DELETE FROM table_name [WHERE ...]改//UPDATE table_name SET usernamezhangsan,password654321,...[WHERE ...];查SELECT 列名 FROM 表名, where条件, group by分组条件, HAVING二级条件, order by排序, LIMIT条件SELECT col_name[,col_name1,col_name2,...] [AS new_col_name][FROM table_name[WHERE where_condition][GROUP BY {col_name | position} [ASE | DESC], ...][HAVING where_condition][ORDER BY {col_name | expr | position} [ASC | DESC], ...][LIMIT {[offset,] row_count | row_count OFFSET offset}]]SET NAMES gbk;//select结果用gbk编码显示不会改变数据库编码方式SELECT * FROM hehe\G;//以表格的形式显示结果子查询SELECT * FROM hehe WHERE id (SELECT id FROM xixi WHERE name zhangsan);假如子查询中的(...)返回结果查过一行则需要用关键字ANY、SOME、ALL三者之一来修饰。SELECT * FROM hehe WHERE price ANY(SELECT price FROM xixi WHERE name goods);ANYSOMEALL、minminmax任意值任意值!任意值其中和!可以用IN和NOT IN代替SELECT * FROM hehe WHERE priceIN(SELECT price FROM xixi WHERE name goods);使用子查询结果//INSERT table_name (col_name1,col_name2,...) SELECT ...连接语法... [LEFT | RIGHT] JOIN 表名 ON 连接条件 ...内连接【JOIN】外连接左外连接【LEFT JOIN】、右外连接【RIGHT JOIN】、全连接【无】自身连接【内连接自身table即可】连接的条件可以使用ON或者WHERE关键字但是一般使用ON来定义连接条件WHERE来定义筛选条件。//双表连接显式SELECT col_name [AS resultId] FROM table_name1 AS t1 JOIN table_name2 AS t2 ON t1.id t2.id WHERE...UPDATE table_name1 AS a JOIN table_name2 AS b ON a.id b.number SET a.name b.name;DELETE t1 FROM table_name1 AS t1 LEFT JOIN (SELECT语句...也可嵌套连接和子查询和WHERE筛选)//双表连接隐式内连接可以省略JOIN左外连接和右外连接不可省略。SELECT col_name [AS resultId] FROM table_name1 AS t1, table_name2 AS t2 ON t1.id t2.id WHERE...//双表外连接把内连接的JOIN改成LEFT JOIN或者RIGHT JOIN即可。//多表连接SELECT col_name FROM table_name1 AS t1JOIN table_name2 AS t2 ON t1.id t2.numberJOIN table_name3 AS t2 ON t1.pid t3.number[...]mysql有4种数据类型(整形、浮点型、字符型、日期时间型)。
