Query to return the Max(Date) and other table fields based on a primary table list - sql

Question

I am hoping somebody out there can help me with a query problem I can’t seem to resolve;
I have two tables;
Table1
T1_ID
T1_Serial
Table2
T2_ID
T1_ID –lookup to Table 1
T2_Date
T2_History
Table1 Data might look something like this;
T1_ID T1_Serial
1, ABC1
2, ABC2
3, ABC3
4, ABC4
Table2 Data might look like this;
T2_ID, T1_ID, T2_Date, T2_History
1, 1, 05/05/15, “Some History1”
2, 1, 05/17/15, “Some History2”
3, 2, 05/09/15, “Some History3”
4, 2, 05/21/15, “Some History4”
5, 3, 05/12/15, “Some History5”
I would like to set up a query to give me the record containing Max(Date) of table History for each record in table Units
Table1.T1_Serial , Max(T2_Date), T2_History;
For this example;
ABC1 05/17/15 “Some History2”
ABC2 05/21/15 “Some History4”
ABC3 05/12/15 “Some History5”
I have constructed the SQL to give me the T1_Serial and Max(Date), which is working correctly;
SELECT Table2.T1_ID, Max(Table2.T2_Date) AS MaxDate
FROM Table2
GROUP BY Table2.T1_ID;
But when I try adding the T2_History to the query I end up getting all the other history besides the Max(Date).
Hope someone can lead me on the right path. Thanks!

Answer 1

I use similar approach as Sam. But removed the T2_ID from the wrapped SQL to avoid issues with the GROUP BY. Also Join by Date.
SQL Fiddle
WITH MaxDate (T1_ID, MaxDate) as
(
SELECT T1_ID, Max(Table2.T2_Date) AS MaxDate
FROM Table2
GROUP BY Table2.T1_ID
)
SELECT T1_Serial, T2_Date, T2_History
FROM
MaxDate
INNER JOIN Table2 ON MaxDate.MaxDate = Table2.T2_Date
INNER JOIN Table1 ON MaxDate.T1_ID = Table1.T1_ID;
vba version fiddle
SELECT tbl_RMAunit.RMA_SN, tbl_History.Hist_Date,tbl_History.Hist_History
FROM (
SELECT RMA_ID, Max(tbl_History.Hist_Date) as MaxDate
FROM tbl_History
Group by tbl_History.RMA_ID
) MaxDate
Inner Join tbl_History on MaxDate.MaxDate = tbl_History.Hist_Date
Inner Join tbl_RMAunit on MaxDate.RMA_ID = tbl_RMAunit.RMA_ID

Answer 2

I found this example for nested queries on VBA. But i couldnt try it. Good luck.
Sub TestNestedQuery()
Dim RS As DAO.Recordset, strSql As String
Dim qdfTemp As QueryDef
Dim qdfNew As QueryDef
Dim strSQL1 as string
Dim strSQL2 as string
strSQL1 = "SELECT RMA_ID, Max(tbl_History.Hist_Date) as MaxDate " & _
"FROM tbl_History " & _
"Group by tbl_History.RMA_ID"
strSQL2 = "SELECT tbl_RMAunit.RMA_SN, tbl_History.Hist_Date,tbl_History.Hist_History " & _
"FROM qryTemp " & _
"Inner Join tbl_History on qryTemp.MaxDate = tbl_History.Hist_Date " & _
"Inner Join tbl_RMAunit on qryTemp.RMA_ID = tbl_RMAunit.RMA_ID "
With CurrentDb()
Set qdfTemp = .CreateQueryDef("qryTemp", strSQL1) '' SQL 1
Set qdfNew = .CreateQueryDef("qryNew", strSQL2)' SQL 2
GetrstTemp qdfNew
''' Delete the two querydefs if necessary
.QueryDefs.Delete qdfTemp.Name
.QueryDefs.Delete qdfNew.Name
End With
End Sub
Function GetrstTemp(qdfTemp As QueryDef)
Dim rstTemp As DAO.Recordset
Dim i As Integer: i = 0
With qdfTemp
Debug.Print .Name
Debug.Print " " & .sql
'' Open Recordset from QueryDef.
Set rstTemp = .OpenRecordset(dbOpenSnapshot)
Do While Not rstTemp.EOF
i = i + 1
Debug.Print rstTemp.Fields("RMA_SN") '' Change the field name
Debug.Print rstTemp.Fields("Hist_Date") '' Change the field name
rstTemp.MoveNext
Loop
Debug.Print
Debug.Print " Number of records = " & _
rstTemp.RecordCount
End With
End Function