通用分页存储过程

数据库还是用Northwind数据库。就用Orders表为例子吧，假设每页都显示10条记录。

我们先查询第一页的数据。

SELECT  *
FROM    ( SELECT    ROW_NUMBER() OVER ( ORDER BY OrderID ) AS RowNumber ,
                    *
          FROM      Orders
        ) T
WHERE   RowNumber BETWEEN 1 AND 10

这里用到一个函数ROW_NUMBER() OVER函数，这个函数的语法是ROW_NUMBER() OVER(PARTITION BY COLUMN ORDER BY COLUMN)

简单的说ROW_NUMBER()从1开始，为每一条分组记录返回一个数字，这里的ROW_NUMBER() OVER (ORDER BY OrderID) 是先把OrderID列升序，再为升序以后的每条记录返回一个序号。 

接下来，查询第二页的数据。

SELECT  *
FROM    ( SELECT    ROW_NUMBER() OVER ( ORDER BY OrderID ) AS RowNumber ,
                    *
          FROM      Orders
        ) T
WHERE   RowNumber BETWEEN 11 AND 20

由此可以推断出，第N页的数据为

SELECT  *
FROM    ( SELECT    ROW_NUMBER() OVER ( ORDER BY OrderID ) AS RowNumber ,
                    *
          FROM      Orders
        ) T
WHERE   RowNumber BETWEEN (N-1)*10+1 AND N*10

写成通用的SQL语句如下：

BEGIN
    DECLARE @PageSize INT     --每页显示条数
    DECLARE @PageIndex INT    --页码（从1开始）
    SET @PageSize = 10
    SET @PageIndex = 2
    SELECT  *
    FROM    ( SELECT    ROW_NUMBER() OVER ( ORDER BY OrderID ) AS RowNumber ,
                        *
              FROM      Orders
            ) T
    WHERE   RowNumber BETWEEN ( ( @PageIndex - 1 ) * @PageSize + 1 )
                      AND     ( @PageIndex * @PageSize )
    ORDER BY OrderID ASC
END

写成存储过程如下：

--存储过程
CREATE PROCEDURE P_GetPagedOrders2
    @PageSize INT ,             --每页显示条数
    @PageIndex INT ,            --页码（从1开始）
    @RecordCount INT OUTPUT ,    --数据总数
    @PageCount INT OUTPUT        --总页数
AS
    BEGIN
        --获取数据总数
        SELECT  @RecordCount = COUNT(1)
        FROM    dbo.Orders
        --计算总页数
        SET @PageCount = @RecordCount / @PageSize
        IF @RecordCount % @PageSize > 0
            BEGIN
                SET @PageCount = @PageCount + 1
            END
        --获取当前页的数据
        SELECT  *
        FROM    ( SELECT    ROW_NUMBER() OVER ( ORDER BY OrderID ) AS RowNumber ,
                            *
                  FROM      Orders
                ) T
        WHERE   RowNumber BETWEEN ( ( @PageIndex - 1 ) * @PageSize + 1 )
                          AND     ( @PageIndex * @PageSize )
        ORDER BY OrderID ASC
    END

测试存储过程

DECLARE    @RecordCount int,
           @PageCount int

EXEC    [P_GetPagedOrders2]
        @PageSize = 10,
        @PageIndex = 2,
        @RecordCount = @RecordCount OUTPUT,
        @PageCount = @PageCount OUTPUT

SELECT    @RecordCount as N'@RecordCount',
        @PageCount as N'@PageCount'

测试结果如下