MySQL重点注意:MySQL 对大小写不敏感!
SQL 分为两个部分:数据操作语言 (DML) 和 数据定义语言 (DDL):
DML 部分:(查询和更新指令)
- SELECT - 从数据库表中获取数据
- UPDATE - 更新数据库表中的数据
- DELETE - 从数据库表中删除数据
- INSERT INTO - 向数据库表中插入数据
DDL 语句:(重要的一些)
- CREATE DATABASE - 创建新数据库
- ALTER DATABASE - 修改数据库
- CREATE TABLE - 创建新表
- ALTER TABLE - 变更(改变)数据库表
- DROP TABLE - 删除表
- CREATE INDEX - 创建索引(搜索键)
- DROP INDEX - 删除索引
主要使用的命令速查:
| 命令 | 语法(部分附有解释) |
| AND / OR | SELECT column_name(s) FROM table_name WHERE condition AND|OR condition |
| ALTER TABLE (add column) | ALTER TABLE table_name ADD column_name datatype |
| ALTER TABLE (drop column) | ALTER TABLE table_name DROP COLUMN column_name |
| AS (alias for column) | SELECT column_name AS column_alias FROM table_name |
| AS (alias for table) | SELECT column_name FROM table_name AS table_alias |
| BETWEEN | SELECT column_name(s) FROM table_name WHERE column_name BETWEEN value1 AND value2 |
| CREATE DATABASE | CREATE DATABASE database_name |
| CREATE INDEX | CREATE INDEX index_name ON table_name (column_name) |
| CREATE TABLE | CREATE TABLE table_name ( column_name1 data_type, column_name2 data_type, ....... ) |
| CREATE UNIQUE INDEX | CREATE UNIQUE INDEX index_name ON table_name (column_name) |
| CREATE VIEW | CREATE VIEW view_name AS SELECT column_name(s) FROM table_name WHERE condition |
| DELETE FROM | DELETE FROM table_name (Note: Deletes the entire table!!)orDELETE FROM table_name WHERE condition |
| DROP DATABASE | DROP DATABASE database_name |
| DROP INDEX | DROP INDEX table_name.index_name |
| DROP TABLE | DROP TABLE table_name |
| GROUP BY | SELECT column_name1,SUM(column_name2) FROM table_name GROUP BY column_name1 |
| HAVING | SELECT column_name1,SUM(column_name2) FROM table_name GROUP BY column_name1 HAVING SUM(column_name2) condition value |
| IN | SELECT column_name(s) FROM table_name WHERE column_name IN (value1,value2,..) |
| INSERT INTO | INSERT INTO table_name VALUES (value1, value2,....)orINSERT INTO table_name (column_name1, column_name2,...) VALUES (value1, value2,....) |
| LIKE | SELECT column_name(s) FROM table_name WHERE column_name LIKE pattern |
| ORDER BY | SELECT column_name(s) FROM table_name ORDER BY column_name [ASC|DESC] |
| SELECT | SELECT column_name(s) FROM table_name |
| SELECT * | SELECT * FROM table_name |
| SELECT DISTINCT | SELECT DISTINCT column_name(s) FROM table_name |
| SELECT INTO (used to create backup copies of tables) | SELECT * INTO new_table_name FROM original_table_nameorSELECT column_name(s) INTO new_table_name FROM original_table_name |
| TRUNCATE TABLE (deletes only the data inside the table) | TRUNCATE TABLE table_name |
| UPDATE | UPDATE table_name SET column_name=new_value [, column_name=new_value] WHERE column_name=some_value |
| WHERE | SELECT column_name(s) FROM table_name WHERE condition |
--来源是W3CSchool想要详细学习可以参考链接:
W3CSchool:SQL 教程
本文详细介绍MySQL对大小写不敏感的特点,并深入讲解了SQL的数据操作语言(DML)和数据定义语言(DDL),包括SELECT、UPDATE、CREATE TABLE等关键命令及其用法,适合SQL初学者和进阶者参考。
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