Mysql入门学习

建库

CREATE DATABASE DB;

引用库

USE bankDB;

建表

##创建用户表
##drop TABLE user_info
CREATE TABLE IF NOT  EXISTS user_info(
user_id INT AUTO_INCREMENT PRIMARY KEY,
user_name NVARCHAR(30),
user_sex NVARCHAR(4)
);

##创建用户卡类型表
##drop TABLE card_type
CREATE TABLE IF NOT  EXISTS card_type(
usertype_id INT AUTO_INCREMENT PRIMARY KEY,
usertype_Name NVARCHAR(30)
);

##创建用户卡信息表
##DROP TABLE user_card
CREATE TABLE IF NOT  EXISTS user_card(
usercard_id INT AUTO_INCREMENT PRIMARY KEY,
usercard_number NVARCHAR(30),
usercard_pwd INT,
usercard_remark TEXT,
usertype_id INT,#外键user_type
user_id INT,#外键user_info
FOREIGN KEY(usertype_id) REFERENCES  card_type(usertype_id) ON DELETE CASCADE,##创建外键关系语句
FOREIGN KEY(user_id) REFERENCES  user_info(user_id) ON DELETE CASCADE ##创建外键关系语句
)
engine=InnoDB CHARACTER SET utf8 COLLATE utf8_general_ci AUTO_INCREMENT=5;##外键事务引擎,数据库字符集,数据库校对规则

录入表数据

##录入用户信息数据
INSERT INTO user_info VALUES (NULL,'张三0','男');
INSERT INTO user_info VALUES (NULL,'张三1','女');
INSERT INTO user_info VALUES (NULL,'张三2','男');
INSERT INTO user_info VALUES (NULL,'张三3','男');
INSERT INTO user_info VALUES (NULL,'张三4','男');
INSERT INTO user_info VALUES (NULL,'张三5','男');
INSERT INTO user_info VALUES (NULL,'张三6','女');
INSERT INTO user_info VALUES (NULL,'张三7','女');
##录入用户卡类型数据
INSERT INTO card_type VALUES (NULL,'信贷卡');
INSERT INTO card_type VALUES (NULL,'借记卡');
INSERT INTO card_type VALUES (NULL,'消费卡');
##录入用户卡数据
INSERT INTO user_card VALUES (NULL,'500226198705088574',123456,'备注',1,1);
INSERT INTO user_card VALUES (NULL,'500226199995088574',123456,'备注',2,1);
INSERT INTO user_card VALUES (NULL,'500226155505088574',123456,'备注',3,1);
INSERT INTO user_card VALUES (NULL,'500226198705088574',123456,'备注',1,2);
INSERT INTO user_card VALUES (NULL,'500226777705088574',123456,'备注',1,3);
INSERT INTO user_card VALUES (NULL,'500226192115088574',123456,'备注',1,4);
INSERT INTO user_card VALUES (NULL,'500226097050488574',123456,'备注',1,6);
INSERT INTO user_card VALUES (NULL,'500226777705088574',123456,'备注',2,3);
INSERT INTO user_card VALUES (NULL,'500226192115088574',123456,'备注',3,4);
INSERT INTO user_card VALUES (NULL,'500226097050488574',123456,'备注',1,8);

数据查询

##分别查询每张表的所有数据
SELECT * FROM user_info;
SELECT * FROM card_type;
SELECT * FROM user_card;
##查询三张表的所有数据
SELECT  * FROM user_info,user_card,card_type ;

######查询卡:信贷卡的用户信息记录#######
##方法一：
SELECT  user_info.user_id,user_info.user_name,user_info.user_sex
FROM user_info,user_card,card_type
WHERE   user_info.user_id=user_card.user_id
AND user_card.usertype_id=card_type.usertype_id
AND card_type.usertype_Name='信贷卡';

##方法二
SELECT * FROM user_info WHERE user_id IN(
SELECT user_id FROM user_card WHERE usertype_id =(
SELECT usertype_id FROM card_type WHERE usertype_Name='信贷卡')
);

##左连接(以user_info为显示基础,user_card没有符合条件则以null填充显示)
SELECT DISTINCT * FROM user_info LEFT JOIN user_card ON user_info.user_id=user_card.user_id;
##右连接(与上面相反)
SELECT DISTINCT * FROM user_info RIGHT JOIN user_card ON user_info.user_id=user_card.user_id;
##内连接(ON等同于where)
SELECT DISTINCT * FROM user_info INNER JOIN user_card ON user_info.user_id=user_card.user_id;

附录

1.判断表是否存在

IF NOT  EXISTS
例：CREATE TABLE IF NOT  EXISTS 表名

2.标识自增列（一般设置主键）

AUTO_INCREMENT
例： user_id INT AUTO_INCREMENT

3.标识主键

PRIMARY KEY
例： user_id INT PRIMARY KEY

4.标识外键（4，5，6一般一起使用）

FOREIGN KEY
例：FOREIGN KEY(要设置的外键字段)

5.外键引用（4，5，6一般一起使用）

REFERENCES
例：REFERENCES 表名（关联字段）

6.设置级联删除（4，5，6一般一起使用）

ON DELETE CASCADE
例： FOREIGN KEY(usertype_id) REFERENCES  card_type(usertype_id) ON DELETE CASCADE

7.设置外键处理引擎（设置在表后面，见表user_card）

ENGINE=InnoDB
例：ENGINE=InnoDB

8.设置外键字符集（设置在表后面，见表user_card）

CHARACTER SET utf8
例： CHARACTER SET utf8

9.设置数据库校对规则（设置在表后面，见表user_card）

COLLATE utf8_general_ci AUTO_INCREMENT=5
例：COLLATE utf8_general_ci AUTO_INCREMENT=5
例：ENGINE=InnoDB CHARACTER SET utf8 COLLATE utf8_general_ci AUTO_INCREMENT=5