Basic knowledge of MySQL database

This note is mainly a summary mysql Database Basics
What we need to master mainly includes information ——> Draw ER chart ——> from ER Figure creating a database table （sql sentence ）
1. conceptual model -ER chart

Change picture to

2. use sql sentence （ Realize operations such as adding, deleting, checking and rebuilding ）

（1） build

CREATE TABLE `wy`.`student` (
  `Sno` VARCHAR(45) NOT NULL,
  `Sname` VARCHAR(5) NOT NULL,
  `Ssex` VARCHAR(2) NOT NULL,
  `Sage` VARCHAR(3) NOT NULL,
  `Sdept` VARCHAR(45) NOT NULL,
  PRIMARY KEY (`Sno`));

INSERT INTO `wy`.`student` (`Sno`, `Sname`, `Ssex`, `Sage`, `Sdept`) VALUES ('200215121', ' Li Yong ', ' male ', '20', 'CS');
INSERT INTO `wy`.`student` (`Sno`, `Sname`, `Ssex`, `Sage`, `Sdept`) VALUES ('200215122', ' Liu Chen ', ' Woman ', '19', 'CS');
INSERT INTO `wy`.`student` (`Sno`, `Sname`, `Ssex`, `Sage`, `Sdept`) VALUES ('200215123', ' Wang min. ', ' Woman ', '18', 'MA');
INSERT INTO `wy`.`student` (`Sno`, `Sname`, `Ssex`, `Sage`, `Sdept`) VALUES ('200515125', ' Zhang Li ', ' male ', '19', 'IS');

The table is as follows ：

（2） increase
INSERT INTO ‘wy’.‘student’ (‘Sno’, ‘Sname’, ‘Ssex’, ‘Sage’, ‘Sdept’) VALUES (‘200215126’, ‘ Zhang Chengmin ’, ‘ male ’, ‘18’, ‘CS’);

（3） Delete

• Delete row
  DELETE FROM ‘wy’.‘student’ WHERE (‘Sno’ = ‘200515125’);
• Delete table
  DROP TABLE Student CASCADE;

(4) Change

UPDATE ‘wy’.‘class’ SET ‘Cdept’ = ‘ School of computer and information engineering ’ WHERE (‘Cid’ = ‘06’);

（5） check
SELECT * FROM wy.class;

ER Figure example