分页sql

​ 我用的是第一种 ，需要两个参数：页大小，页数

表中主键必须为标识列，[ID] int IDENTITY (1,1) 1.分页方案一：(利用Not In和SELECT TOP分页) 语句形式：

SELECT TOP 10 *
FROM TestTable
WHERE (ID NOT IN
          (SELECT TOP 20 id
         FROM TestTable
         ORDER BY id))
ORDER BY ID


SELECT TOP 页大小 *
FROM TestTable
WHERE (ID NOT IN
          (SELECT TOP 页大小*页数 id
         FROM 表
         ORDER BY id))
ORDER BY ID
   2.分页方案二：(利用ID大于多少和SELECT TOP分页）
语句形式：  
SELECT TOP 10 *
FROM TestTable
WHERE (ID >
          (SELECT MAX(id)
         FROM (SELECT TOP 20 id
                 FROM TestTable
                 ORDER BY id) AS T))
ORDER BY ID


SELECT TOP 页大小 *
FROM TestTable
WHERE (ID >
          (SELECT MAX(id)
         FROM (SELECT TOP 页大小*页数 id
                 FROM 表
                 ORDER BY id) AS T))
ORDER BY ID
  3.分页方案三：(利用SQL的游标存储过程分页)

create  procedure SqlPager
@sqlstr nvarchar(4000), --查询字符串
@currentpage int, --第N页
@pagesize int --每页行数
as
set nocount on
declare @P1 int, --P1是游标的id
 @rowcount int
exec sp_cursoropen @P1 output,@sqlstr,@scrollopt=1,@ccopt=1, @rowcount=@rowcount output
select ceiling(1.0*@rowcount/@pagesize) as 总页数--,@rowcount as 总行数,@currentpage as 当前页
set @currentpage=(@currentpage-1)*@pagesize+1
exec sp_cursorfetch @P1,16,@currentpage,@pagesize
exec sp_cursorclose @P1
set nocount off

其它的方案：如果没有主键，可以用临时表，也可以用方案三做，但是效率会低。 建议优化的时候，加上主键和索引，查询效率会提高。

通过SQL 查询分析器，显示比较：我的结论是: 分页方案二：(利用ID大于多少和SELECT TOP分页）效率最高，需要拼接SQL语句 分页方案一：(利用Not In和SELECT TOP分页) 效率次之，需要拼接SQL语句 分页方案三：(利用SQL的游标存储过程分页) 效率最差，但是最为通用

还有另一种，内置了行号：

 string SqlFormat, SqlAll, SqlBind;

            SqlFormat = "select * from ({0}) a where a.rownum between ({1}-1)*{2}+1 and {1}*{2}";

            SqlAll = "SELECT (ROW_NUMBER() OVER(ORDER BY " + StrOrder + ")) AS ROWNUM, A.* FROM ( " + StrSql + ") A";

            SqlBind = string.Format(SqlFormat, SqlAll, CurrentPage, PageSize);

            DataTable dt = dbop.GetDataSet(SqlBind).Tables[0];
            ```
           
dapper中的分页方法：

     ```
       /// <summary>
       /// 分页
       /// </summary>
       /// <param name="pageIndex">当前页</param>
       /// <param name="pageSize">每页大小</param>
       /// <param name="totalCount">总记录数</param>
       /// <returns></returns>
       public IEnumerable<NoticeModel> GetPage(int pageIndex,int pageSize,out int totalCount)
       {
           StringBuilder strSql = new StringBuilder();
           strSql.Append("select * from(select RN=ROW_NUMBER() OVER(ORDER BY Id desc),* from tb_NoticeBoard) as a ");
           strSql.Append("where a.RN between (@pageIndex-1)*@pageSize+1 and @pageIndex*@pageSize ");
           var lt= connection.Query<NoticeModel>(strSql.ToString(), new { @pageIndex = pageIndex, @pageSize = pageSize });
           totalCount = GetTotalCount();
           return lt;
       }
​