如何在SQL查询中启动变量？

Question

我做了一个查询以获得某个列的最大值

sSQLmax = "SELECT MAX([tablename]!rowname) as MaxNum FROM [tablename]"

.

我想使用maxnum值。我在一个msgbox中尝试了它，给了我一个空白值。我尝试了所有这些：

MsgBox "MaxNum" & MaxNum

MsgBox "MaxNum" & sSQLMAX.MaxNum

MsgBox "MaxNum" & sSQLMAX!MaxNum

.

更多的代码

Dim db As DAO.Database, rst As DAO.Recordset
Set db = CurrentDb
Set rst = db.OpenRecordset(sSQLmax)

.

但没有工作，我相信它的简单，但它逃脱了我

Answer 1

使用代码，您只能将变量设置为字符串。你实际上并没有与之做任何事情。这可能是您在寻找的内容：

Dim db As DAO.Database, rst As DAO.Recordset, sSQLmax As String
sSQLmax = "SELECT MAX([tablename].rowname) as MaxNum FROM [tablename]"
Set db = CurrentDb

Set rst = db.OpenRecordset(sSQLmax, dbOpenDynaset)

If (rst.RecordCount <> 0) Then
  rst.MoveFirst
  MsgBox "MaxNumber: " & rst.Fields("rowname")
End If

.

Answer 2

尝试dmax函数

Dim result as String
result = DMax("[COLUMN NAME]", "[TABLE NAME]")

.