Sql common usage

最新推荐文章于 2025-09-08 20:55:49 发布

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最新推荐文章于 2025-09-08 20:55:49 发布

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文章标签：数据库

原文链接：http://www.cnblogs.com/epirus/archive/2012/07/30/2615289.html

本文详细介绍了SQL语言的基本语法，包括创建表、查看表结构、删除和修改表、使用索引、创建和使用数据库、更新和选择数据、条件查询、模糊查询、分页查询、多表查询以及数据安全等关键概念。

1.create table table_name(var1 type1,var2 type2)

CREATE TABLE Persons

( Id_P int, LastName varchar(255), FirstName varchar(255), Address varchar(255), City varchar(255) )
create table if not exists table_name(same ....);
2.desc table_name //to see the structure of table

3.delete from table_name where id>1 and id <10;
4.drop table table_name;
5.drop index index_name on table_name;
6.utf-8 3byte gbk 2byte so->varchar(12) have 6 chinese words and utf-8->varchar(12) have 3 chinese words
7.create database database_name; use database_name;
8.update table_name set field='value" where condition(id>=5 && id <=19);
　　update table_name set field=field+1 where id='value';
9.delete from table_name where
10.select table_name.field,table_name.field from table_name
　　select field as alias from table_name
　　select field1,field2,field2*0.8 as discount from table_name
　　select * from table_name where id between 10 and 20;
　　select * from table_name where id not between 10 and 20;
　　select * from table_name where id in(10,29,32);
11. _ present a char and % present any chars;
　　select * from table_name where name like "%ly";//选出已ly结尾的
　　select * from table_name where name not like ""//
12.select * from table_name where id=(select max(id)from table_anem);
//It's good solution
13.show databases; //show databases
14.use databases;//use database;
15.select distinct name from table_name //display only once and remove the dumplicate
16.select age from table_name where age>12;//数值不使用单引号，字符使用单引号
17.select * from table_name order by age;//根据年龄默认升序排列