数据库mysql

一、mysql常用语句

登录MySQL	mysql -u root -p
列出所有数据库	SHOW DATABASES;
创建一个新数据库	CREATE DATABASE test;
删除一个数据库	DROP DATABASE test;
对一个数据库进行操作时	USE test;
列出当前数据库的所有表	SHOW TABLES;
要查看一个表的结构	DESC students;
创建表	CREATE TABLE
删除表	DROP TABLE
退出MySQL	EXIT

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二、sql常用语句

1. 查询

所有数据	SELECT * FROM students;
条件查询	SELECT * FROM students WHERE score >= 80;
更多的条件	SELECT * FROM students WHERE (score < 80 OR score > 90) AND gender = ‘M’;
从students表中返回id、score和name这三列：	SELECT id, score, name FROM students;
排序	SELECT id, name, gender, score FROM students ORDER BY score;
加上DESC表示“倒序”	SELECT id, name, gender, score FROM students ORDER BY score DESC;

2. 插入

插入一条新记录	INSERT INTO students (class_id, name, gender, score) VALUES (2, ‘大牛’, ‘M’, 80);
一次性添加多条记录	INSERT INTO students (class_id, name, gender, score) VALUES (1, ‘大宝’, ‘M’, 87), (2, ‘二宝’, ‘M’, 81);

3. 修改

基本语法	UPDATE students SET name=‘大牛’, score=66 WHERE id=1;
更新字段时可以使用表达式	UPDATE students SET score=score+10 WHERE score<80;

4. 删除

删除students表中id=1的记录	DELETE FROM students WHERE id=1;