DataGrid连接Access的快速分页法（3）——SQL语句的选用（降序）
三、降序
（1）@PageIndex <= @FirstIndex
SELECT TOP @PageSize @QueryFields
FROM @TableName
WHERE @Condition
ORDER BY @PrimaryKey DESC
（2）@FirstIndex < @PageIndex <= @MiddleIndex
SELECT TOP @PageSize @QueryFields
FROM @TableName
WHERE @PrimaryKey < (
SELECT MIN(@PrimaryKey) FROM (
SELECT TOP @PageSize*@PageIndex @PrimaryKey
FROM @TableName
WHERE @Condition
ORDER BY @PrimaryKey DESC
) TableA
) WHERE @Condition
ORDER BY @PrimaryKey DESC
（3）@MiddleIndex < @PageIndex < @LastIndex
SELECT * FROM (
SELECT TOP @PageSize @QueryFields
FROM @TableName
WHERE @PrimaryKey > (
SELECT MAX(@PrimaryKey) FROM (
SELECT TOP (@RecordCount-@PageSize*(@PageIndex+1)) @PrimaryKey
FROM @TableName
WHERE @Condition
-- ORDER BY @PrimaryKey ASC
) TableA
) WHERE @Condition
-- ORDER BY @PrimaryKey ASC
) TableB
ORDER BY @PrimaryKey DESC
（4）@PageIndex >= @LastIndex
SELECT * FROM (
SELECT TOP (@RecordCount-@PageSize*@LastIndex) @QueryFields
FROM @TableName
WHERE @Condition
ORDER BY @PrimaryKey ASC
) TableA
ORDER BY @PrimaryKey DESC
四、总结
通过上面的讨论，相信大家应该看到了该分页方法的优势所在。在下一篇中，我将给大家一个动态生成上面 SQL 语句的类。
作者：黎波
