根据Access中的其他字段查找下一个较低的数字

Question

我有一个包含这样数据的表：

MainID, MainNumber, MainType
1       250         Hours
2       500         Hours
3       1000        Hours
4       5000        Miles
5       20000       Miles

当我为MainNumber和MainType设置值时，我需要为该MainType提取下一个较低的MainNumber。

这是我的代码：

SQL = "SELECT T2.MainID, Max([t2.MainNumber]) AS PreviousCycle"
SQL = SQL & " FROM tblMainType AS T1 LEFT JOIN tblMainType as T2 on T1.MainNumber > T2.MainNumber"
SQL = SQL & " WHERE T1.mainType = '" & mType & "' AND T1.MainNumber = " & MainNumber
SQL = SQL & " Group By T2.MainID;"

奇怪的是它可以工作几个小时而不是几英里？我的代码出了什么问题？

Answer 1

要查找下一个最高的数字，我会按降序对字段进行排序并获取TOP 1值。

Sql = "SELECT TOP 1 tblMainType.MainID, tblMainType.MainNumber " & _
      "FROM tblMainType " & _
      "WHERE (((tblMainType.MainNumber)< " & mType & ") AND ((tblMainType.MainType)='" & MainNumber & "')) " & _
      "ORDER BY tblMainType.MainNumber DESC;"

Answer 2

我希望这样的查询：

SELECT TOP 1 MainID, MainNumber 
FROM tblMainType 
WHERE MainType = @MainType AND
      MainNumber >= @MainNumber
ORDER BY MainNumber DESC, MainId;

@MainType和@MainNumber是您输入的值。