MySQL入门：库表操作全攻略
初识MySQL：库和表的操作
MySQL是一种广泛使用的关系型数据库管理系统，掌握库和表的操作是学习MySQL的基础。以下内容将详细介绍MySQL中库和表的创建、修改、删除等基本操作。
数据库操作
创建数据库
使用CREATE DATABASE语句创建数据库，语法如下：
CREATE DATABASE database_name;
例如，创建名为test_db的数据库：
CREATE DATABASE test_db;
查看数据库
查看所有数据库列表：
SHOW DATABASES;
选择数据库
在操作表之前，需要先选择数据库：
USE database_name;
删除数据库
删除数据库会移除所有相关数据，需谨慎操作：
DROP DATABASE database_name;
表操作
创建表
使用CREATE TABLE语句创建表，需指定列名和数据类型：
CREATE TABLE table_name (
column1 datatype constraints,
column2 datatype constraints,
...
);
例如，创建名为users的表：
CREATE TABLE users (
id INT PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(50) NOT NULL,
email VARCHAR(100) UNIQUE,
age INT
);
查看表结构
查看表的结构信息：
DESCRIBE table_name;
修改表
使用ALTER TABLE语句修改表结构：
- 添加列：
ALTER TABLE table_name ADD column_name datatype;
- 修改列数据类型：
ALTER TABLE table_name MODIFY column_name new_datatype;
- 删除列：
ALTER TABLE table_name DROP COLUMN column_name;
重命名表
修改表名：
RENAME TABLE old_name TO new_name;
删除表
删除表及其数据：
DROP TABLE table_name;
数据操作
插入数据
向表中插入数据：
INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...);
例如：
INSERT INTO users (name, email, age) VALUES ('Alice', 'alice@example.com', 25);
查询数据
查询表中的数据：
SELECT * FROM table_name;
或指定列：
SELECT column1, column2 FROM table_name;
更新数据
修改表中的数据：
UPDATE table_name SET column1 = value1 WHERE condition;
例如：
UPDATE users SET age = 26 WHERE name = 'Alice';
删除数据
删除表中的数据：
DELETE FROM table_name WHERE condition;
例如：
DELETE FROM users WHERE id = 1;
索引操作
创建索引
提高查询效率：
CREATE INDEX index_name ON table_name (column_name);
删除索引
移除索引：
DROP INDEX index_name ON table_name;
通过以上操作，可以完成MySQL中库和表的基本管理。熟练掌握这些操作是进一步学习MySQL高级功能的基础。
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