1MySQL语法基础--增删改查

Posted 2021-03-10 zhujing666

 建表语句

 2 CREATE TABLE `students`(‘id‘INT NOT NULL AUTO_INCREMENT,`name`VARCHAR(200)NOT NULL);
 3 
 4 USE `school`;
 5 
 6 CREATE TABLE `students`(
 7 `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
 8 `name` VARCHAR(20) NOT NULL,
 9 `nickname` VARCHAR(20) NULL,
10 `sex` CHAR(1) NULL,
11 `in time` DATETIME NULL
12 );

 

插入语句

INSERT INTO  `table`  VALUE(S)(...);

 

INSERT INTO `students` VALUE(1,‘张三‘,‘三哥‘,‘男‘,now());

　如果有空置，那么可以写成以下代码：

INSERT INTO `students`(`name`,`nickname`) VALUE(‘张三‘,‘三哥‘);

　如果插入多条信息呢

INSERT INTO `students`(`name`,`nickname`) VALUES
  (‘张三2‘,‘三哥2‘),
  (‘张三3‘,‘三哥3‘),
  (‘张三2‘,‘三哥2‘)
;

 

查询语句

SELECT

    select_expr,...

SELECT * FROM `students`;

or

SELECT `id`,`name`,`nickname`FROM `students` WHERE `sex`=‘男‘;

倒序

SELECT `id`,`name`,`nickname`FROM `students` WHERE `sex`=‘男‘ ORDER BY `id` DESC;　　

分页

SELECT `id`,`name`,`nickname`FROM `students` WHERE `sex`=‘男‘ ORDER BY `id` DESC LIMIT 4,2 ;

 

 

修改语句

UPDATE  table_references

    SET col_name1 = expr1[,col_name2=expr2...]　

[WHERE where_definition]　

UPDATE `students` SET `sex` =‘女‘ WHERE `sex`=‘男‘;

UPDATE `students` SET `sex` =‘女‘, `nickname` =‘没有昵称‘;

　　

删除

DELETE FROM　

DELETE FROM `students` WHERE `sex`=‘男‘;