一、数据库操作
创建数据库
CREATE DATABASE database_name;
删除数据库
DROP DATABASE database_name;
USE database_name;
查看所有数据库
SHOW DATABASES;
二、表操作
创建表
CREATE TABLE table_name (
column1 datatype [约束],
column2 datatype [约束],
...
);
删除表
DROP TABLE table_name;
修改表结构
添加列：
ALTER TABLE table_name ADD column_name datatype;
删除列：
ALTER TABLE table_name DROP COLUMN column_name;
修改列类型：
ALTER TABLE table_name MODIFY column_name new_datatype;
查看表结构
DESCRIBE table_name; -- MySQL
三、数据操作
插入数据
INSERT INTO table_name (column1, column2, ...)
VALUES (value1, value2, ...);
查询数据
SELECT column1, column2 FROM table_name WHERE condition;
SELECT * FROM table_name; -- 查询所有数据
更新数据
UPDATE table_name
SET column1 = value1, column2 = value2
WHERE condition;
删除数据
DELETE FROM table_name WHERE condition;
四、查询进阶
条件筛选
WHERE, AND, OR, NOT, IN, BETWEEN, LIKE
排序
SELECT * FROM table_name ORDER BY column1 ASC|DESC;
分组与聚合
SELECT column, COUNT(*), AVG(column)
FROM table_name
GROUP BY column
HAVING condition;
连接查询
-- 内连接
SELECT * FROM table1
INNER JOIN table2 ON table1.id = table2.foreign_id;
-- 左连接
SELECT * FROM table1
LEFT JOIN table2 ON table1.id = table2.foreign_id;
五、索引操作
创建索引
CREATE INDEX index_name ON table_name (column);
删除索引
ALTER TABLE table_name DROP INDEX index_name;
六、权限管理
创建用户
CREATE USER 'username'@'host' IDENTIFIED BY 'password';
授权
GRANT SELECT, INSERT ON database_name.* TO 'username'@'host';
撤销权限
REVOKE INSERT ON database_name.* FROM 'username'@'host';
七、事务管理
开启事务
BEGIN TRANSACTION; -- 或 START TRANSACTION;
提交事务
COMMIT;
回滚事务
ROLLBACK;
