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  • SQL Server 常用关键字

    SQL 建库 建表

    --1.创建一个数据库
    create database School;
    --删除数据库
    drop database School;
    --创建数据库的时候指定一些选项。
    create database School
    on primary
    (
        name='School',
        filename='C:Program FilesSQLMSSQL12.MSSQLMSSQLDATASchool.mdf',
        size=5MB,
        --filegrowth=10MB,
        filegrowth=10%,--按照文件的百分比来增长
        maxsize=100MB
    )
    log on
    (
        name='School_log',
        filename='C:Program FilesSQLMSSQL12.MSSQLMSSQLDATASchool.ldf',
        size=3MB,
        filegrowth=3%,
        maxsize=20MB
    )
    
    --切换数据库
    use School;

    TOP 

    select top 10 * from student            查询前十条
    
    select top 10 percent * from student    查询前10%

    Distinct

    select distinct * from student   查询不重复

    Avg Count Sum Min MAx

    select AVG(ID) from student   平均数
    select COUNT(ID) from student 总数
    select Sum(ID) from student   求和
    select Max(ID) from student   求最大数
    select Min(ID) from student   求最小

    Where And Or

    select * from student where ID>90 and ID<100 and ID%2=0
    
    select * from student where ID>100 or ID<10 and ID%2!=0

    模糊查询 Like   Not Like % _

    select * from student where Name  like '%三%'        查询带有三的
    select * from student where Name  not like '%三%'    查询不带有三的
    select * from student where Name  like '三%'         查询三开头的
    select * from student where Name  like '%三'         查询三结尾的
    select * from student where Name  like '_ 三 %'      查询第二个为三的

     Order By   where  desc asc 排序

    select * from NT_User order by UserAge  按年龄大小排序
    
    select * from NT_User order by UserAge asc  降序
    select * from NT_User order by UserAge desc 升序

    Group By  Having 分组 (要和聚合函数一起使用)

    select UserGender from NT_User group by UserGender  按性别分成三组
    select UserGender, Count(*) from NT_User group by UserGender 查询三组性别的每个的个数

    select UserGender,COUNT(*) from NT_User group by UserGender having COUNT(*) >1000 查询三组性别的每个的个数大于1000的

     Union  Union All

    select Name from Student union all select Name from Teacher  两表联查 所有的
    
    select Name from Student union select Name from Teacher      两表联查 去除重复的

    Select Into  Insert Into

    select * into teacher from Student          创建Teacher表 并把Student表里面的数据复制到Teacher表中
    
    insert into teacher select * from Student   把Student表里面的数据复制到Teacher表中

     Inner Join on 两表联查

    select A.Content,B.UserName from CLN_Resource as A inner join NT_User as B on A.UserID =B.UserID

    select * from CLN_Resource inner join NT_User on CLN_Resource.UserID=NT_User.UserID
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  • 原文地址:https://www.cnblogs.com/myshowtime/p/5898094.html
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