访问-是否基于唯一键汇总表值？

Question

I'm a beginner to Access. I have a routing table that includes a list of cable trays, as well as the cables that run through those trays. A sample of the data is as follows:

tray        Usable Area    cable                Total Cable Area (mm^2)
CM1001            25000    1-3/C-00AWG-Cu-TECK                  660.19
CM1001            25000     1-3/C-4AWG-Cu-TECK                  572.27
CM1001            25000    1-3/C-14AWG-Cu-TECK                  490.63
TC-100D.2         15600   1-3/C-750AWG-Al-TECK                1,017.36
TM-001.7B         72000   1-3/C-750AWG-Al-TECK                1,017.36
TM-001A.1         10000   1-3/C-750AWG-Al-TECK                1,017.36
TM-001A.2         90000     1-3/C-8AWG-Cu-TECK                  530.66
TM-001A.3         90000   1-3/C-750AWG-Al-TECK                1,017.36

The tray field contains both unique and duplicate values. The duplicate values are considered to be a single tray, just with multiple types of cables running through it (in the cable column). My goal is to sum up the Total Cable Area for a single tray, even if that tray is in fact a number of duplicate entries. For example, the Total Cable Area for tray CM1001 is 1723.06mm², TM-001A.1 is 1017.36mm², and TM-001A.2 is 530.66mm². I will then compare that Total Cable Area to the Usable Area of the tray, to see if the tray is full.

My question is: is there some kind of easy Access query I can run to sum up the values in the Total Cable Area column if there are duplicate 'tray' rows, but just display the value in Total Cable Area is the tray is a unique row? The Usable Area and cable fields are ultimately unimportant when creating this new query. Ideally, my new query would look like:

tray              Total Cable Area (mm^2)
CM1001                           1,723.06
TC-100D.2                        1,017.36
TM-001.7B                        1,017.36
TM-001A.1                        1,017.36
TM-001A.2                          530.66
TM-001A.3                        1,017.36

If there isn't some kind of general query type that I simply didn't know about, would you be willing to provide some starting points on how to accomplish this with VBA? I'm familiar with VBA, just not with Access.

Thank you so much!

Answer 1

You need to select the tray column, the Sum of Total Cable Area (mm^2) , and group by tray .

SELECT [Total Cable Area (mm^2)], SUM([tray]) AS [tray]
FROM [MyTable]
GROUP BY [Total Cable Area (mm^2)]

Answer 2

I wrote a solution in VBA, but it writes the results to another table, which might not be proper form. I've included it below if anyone in the future wants it, but Mat's solution is definitely better.

Sub sum_duplicate_trays()

Dim rs_qry As DAO.Recordset
Dim rs_fill As DAO.Recordset
Set rs_qry = CurrentDb.OpenRecordset("qryCable_Area")
Set rs_fill = CurrentDb.OpenRecordset("tblTray_Fill")

'deletes contents on tblTray_Fill, since it will be replaced below.
DoCmd.SetWarnings False
DoCmd.RunSQL "DELETE * FROM tblTray_Fill"
DoCmd.SetWarnings True

If Not (rs_qry.EOF And rs_qry.BOF) Then
    rs_qry.MoveFirst
    Do Until rs_qry.EOF = True
        'sees if current tray already exists in Fill table (which contains only uniques)
         rs_fill.Index = "tray"
         rs_fill.Seek "=", rs_qry!tray
            If rs_fill.NoMatch Then
               rs_fill.AddNew
               rs_fill!tray = rs_qry!tray
               rs_fill!cable_area = rs_qry![Total Cable Area (mm^2)]
               rs_fill.Update
            Else 'already existing
               rs_fill.Edit
               rs_fill!cable_area = rs_fill!cable_area + rs_qry![Total Cable Area (mm^2)]
               rs_fill.Update
            End If
        rs_qry.MoveNext
    Loop
Else
    MsgBox "Error: the Cable Area query is empty."
End If
End Sub