示例：

https://www.cnblogs.com/fengxiaojiu/p/7994124.html

SQL：

select astart,avg(aid) a from air group by astart
select dateadd(yy,1, '2008-9-10')//2009-09-10 00:00:00.000
select len('我們快放假了.') a//7
select lower('Beautiful')//upper
select round(13.4321,2)//13.4300
select round(13.4567,-1)//10.0000
Select dateAdd(dd,-1,getdate())//一天前

sql函式：

select distinct aend from air--distinct 去掉重複值

select getdate()--獲取系統的當前時間

select YEAR('2009-09-01') --獲取年份

select MONTH('2009-08-15')--獲取月份

select DAY('2009-09-12')--獲取日期
select right('abcd',3)--從右開始往左擷取幾個
select left('abcd',3)--從左開始往右擷取幾個
select datalength('好好學習')--返回位元組的個數//8

分頁：

--pageSize  每頁顯示多少
--pageIndex  頁碼
--i=(@pageIndex-1)*@pageSize
--(1-1)*2=0
--(2-1)*2=2
--(3-1)*2=4
--(4-1)*2=6
-- (頁碼-1)*每頁顯示多少=裡面top
select  top 2--pageSize
 * from air where aid not in(
select  top 6 --i
aid from air order by aid  asc) 
 order by aid asc
 

模糊分頁：

--pageSize  每頁顯示多少
--pageIndex  頁碼
--i=(@pageIndex-1)*@pageSize
--(1-1)*2=0
--(2-1)*2=2
--(3-1)*2=4
--(4-1)*2=6
-- (頁碼-1)*每頁顯示多少=裡面top
select  top 2--pageSize
 * from myuser where hid not in(
select  top 0 --i
hid from myuser where hname like '%地%'
union
select hid from myuser where hname not like '%地%'
) 


 order by hid asc
 
 
 select * from myuser where hname like '%地%'
 

儲存過程分頁：

create procedure fy @pageSize int,@pageIndex int
--pageSize  每頁顯示多少
--pageIndex  頁碼
as
declare @i int
set @i=(@pageIndex-1)*@pageSize
declare @sql varchar(999)
set @sql='select  top '+cast(@pageSize as varchar)+' * from 
stuInfo where stuNo not in
(
	select  top '+cast(@i as varchar)+' stuno from 
	stuInfo order by stuSeat asc
)  order by stuseat asc'
exec(@sql)


exec fy 3,3
--            顯示第幾頁    每頁顯示多少條
--第一頁     裡面的top  0   外面的top 2
--第二頁     裡面的top  2   外面的top 2
--第三頁     裡面的top  4   外面的top 2
--第四頁     裡面的top  6   外面的top 2
--假設傳遞一個引數（每頁顯示多少條）
(1-1)*4=0
(2-1)*4=4
(3-1)*3=6
(4-1)*2=6
 (頁碼-1)*每頁的條目數=裡面的top

java：

package com.dao;

import java.sql.Connection;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.entity.User;
import com.util.DBhelper;

public class Dao {

	public int getMax(String str){
		int nn=0;
		Connection con=null;
		PreparedStatement pre=null;
		ResultSet res=null;
		try {
		con=DBhelper.getCon();
		 String sql="select count(*) from myuser where hname like '%"+str+"%' " ;
			pre=con.prepareStatement(sql);
			res=pre.executeQuery();
		 if (res.next()) {
			nn=res.getInt(1);
		}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		finally{
			
			DBhelper.myClose(con, pre,res);
		}
		return nn;
		
		
	}
	
	public List<User> GetAll(int index,String str){
		List<User> ml=new ArrayList<User>();
		Connection con=null;
		PreparedStatement ps=null;
		ResultSet rs=null;
		int size=2;
		int start=(index-1)*size;
		try {
			con=DBhelper.getCon();
			String sql="select  top 2 * from myuser where hid not in(" +
			"select hid from myuser where hname not like '%"+str+"%' " +
					" union " +
					" select  top "+start+" hid from myuser where hname like '%"+str+"%')";
			ps=con.prepareStatement(sql);
			rs=ps.executeQuery();
			while(rs.next()){
				User n=new User();
				n.setHid(rs.getInt(1));
				n.setHname(rs.getString(2));
				ml.add(n);
			}
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
		finally{
			DBhelper.myClose(con, ps, rs);
		}
		return ml;
	}
	
}