Getting started with Mysql

Build a library

CREATE DATABASE DB;

Reference library

USE bankDB;

build table

##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

input table data

##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);

data query

##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;

appendix

1. Determine whether the table exists

IF NOT  EXISTS
例：CREATE TABLE IF NOT  EXISTS 表名

2. Identify the auto-increment column (generally set the primary key)

AUTO_INCREMENT
例： user_id INT AUTO_INCREMENT

3. Identify the primary key

PRIMARY KEY
例： user_id INT PRIMARY KEY

4. Identify foreign keys (4, 5, 6 are generally used together)

FOREIGN KEY
例：FOREIGN KEY(要设置的外键字段)

5. Foreign key references (4, 5, 6 are generally used together)

REFERENCES
例：REFERENCES 表名（关联字段）

6. Set cascade deletion (4, 5, 6 are generally used together)

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

7. Set the foreign key processing engine (set behind the table, see table user_card)

ENGINE=InnoDB
例：ENGINE=InnoDB 

8. Set the foreign key character set (set after the table, see table user_card)

CHARACTER SET utf8
例： CHARACTER SET utf8

9. Set the database proofing rules (set after the table, see table 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