access|datagrid|分页|语句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。