Mixed scenarios in MS Access - ms-access

Question

This is my table [Property]:
Loanno Balance amount PropertyType
1001045 308731.770000 1
1001045 2007700.740000 2
1001045 3087318905.770 3
1001045 308731.770000 4
1001046 306589.67 1
1001046 456321.23 1
1001046 6932542.89 1
1001047 582563.56 1
1001047 965421.34 2
1001048 567894.34 1
1001048 567894.34 2
I have to get the property type for a [Loanno] having highest balance amount.
If there is a tie in the highest balance amount and if the Property type for the loannumber is different then for that Loan number I have to populate property type as '8'.
So my final Output should look like this:
Loanno PropertyType
1001045 3
1001046 1
1001047 2
1001048 8
Edit
This is what I tried, but I am getting duplicate records.
SELECT DISTINCT
LT.LOANNO,
IIF(COUNTS.MAX_BALANCE > 1, 8,LT.PROPERTY_TYPE) AS PROPERTY_TYPE1
FROM
PROPERTY LT
INNER JOIN
(
SELECT
DISTINCT_ROWS.LOANNO,
COUNT(DISTINCT_ROWS.MaxBalance) AS MAX_BALANCE
FROM
(
SELECT DISTINCT
L.LOANNO,
MaxBalance
FROM
PROPERTY AS L
INNER JOIN
(
SELECT
LOANNO,
MAX(BALANCE_AMOUNT) AS MaxBalance
FROM PROPERTY
GROUP BY LOANNO
) AS SUB
ON (L.LOANNO=SUB.LOANNO)
AND (L.BALANCE_AMOUNT=SUB.MaxBalance)
) AS DISTINCT_ROWS
GROUP BY DISTINCT_ROWS.LOANNO
) AS COUNTS
ON LT.LOANNO=COUNTS.LOANNO
GROUP BY LT.LOANNO, IIF(COUNTS.MAX_BALANCE > 1, 8, LT.PROPERTY_TYPE)

Answer 1

Your query requirements are challenging for Access SQL. A custom VBA function would allow you to use a simpler SELECT statement, but brings issues which may be unacceptable for you:
A UDF (user-defined function) can only be used in a query run within an Access session ... not when you use other code (.Net, Java, PHP, VBScript, etc) to connect to the db and run your query.
UDFs can be slow.
If you can use a UDF, this query using the GetPropertyType function (see below) returns what you asked for. Note I used tblProperties as the table name because Property is a reserved word. Also I assumed Long for the data type of Loanno, Currency for Balance_amount, and Long for Property_Type.
SELECT
sub.Loanno,
GetPropertyType(sub.Loanno,sub.MaxBalance) AS PropertyType
FROM
(
SELECT
Loanno,
Max(Balance_amount) AS MaxBalance
FROM tblProperties
GROUP BY Loanno
) AS sub
ORDER BY sub.Loanno;
This is the function, which I tested with Access 2007.
Public Function GetPropertyType(ByVal pLoanno As Long, _
ByVal pBalance_amount As Currency) As Long
Const cstrQdf As String = "qryLoanPropertyTypesCount"
Dim db As DAO.database
Dim qdf As DAO.QueryDef
Dim lngReturn As Long
Set db = CurrentDb
Set qdf = db.QueryDefs(cstrQdf)
qdf.Parameters("which_Loanno") = pLoanno
qdf.Parameters("which_Balance_amount") = pBalance_amount
If qdf.OpenRecordset()(0) > 1 Then
lngReturn = 8
Else
lngReturn = DLookup("Property_Type", "tblProperties", _
"Loanno=" & pLoanno & " AND Balance_amount=" & _
pBalance_amount)
End If
Set qdf = Nothing
Set db = Nothing
GetPropertyType = lngReturn
End Function
The function uses this saved parameter query, qryLoanPropertyTypesCount:
PARAMETERS which_Loanno Long, which_Balance_amount Currency;
SELECT Count(*) AS num_PropertyTypes
FROM
(
SELECT DISTINCT
p.Loanno,
p.Balance_amount,
p.Property_Type
FROM tblProperties AS p
WHERE
p.Loanno = [which_Loanno]
AND p.Balance_amount = [which_Balance_amount]
) AS sub;

Answer 2

Here's how I built up the query:
Step 1: Create a query to find the maximum balance for each [Loanno] and save that query as [Loanno_MaxBalance]:
SELECT
Loanno,
MAX([Balance amount]) AS MaxBalance
FROM [Property]
GROUP BY Loanno
Step 2a: Create a query to count the number of rows that have the maximum balance, using our saved query above to keep things simple:
SELECT
[Property].Loanno,
[Property].[Balance amount],
COUNT(*) AS RowCount
FROM
[Property]
INNER JOIN
[Loanno_MaxBalance]
ON Loanno_MaxBalance.Loanno=[Property].Loanno
AND Loanno_MaxBalance.MaxBalance=[Property].[Balance amount]
GROUP BY [Property].Loanno, [Property].[Balance amount]
Step 2b: That doesn't look too scary, so let's incorporate the SQL from Step 1 as a subquery:
SELECT
[Property].Loanno,
[Property].[Balance amount],
COUNT(*) AS RowCount
FROM
[Property]
INNER JOIN
(
SELECT
Loanno,
MAX([Balance amount]) AS MaxBalance
FROM [Property]
GROUP BY Loanno
) AS Loanno_MaxBalance
ON Loanno_MaxBalance.Loanno=[Property].Loanno
AND Loanno_MaxBalance.MaxBalance=[Property].[Balance amount]
GROUP BY [Property].Loanno, [Property].[Balance amount]
So now this query stands on its own, and we don't need to keep [Loanno_MaxBalance] as a separate saved query in Access.
We'll save the above query as [Loanno_MaxBalance_Count].
Step 3a: Now to derive the [PropertyType] values using the [Property] table and the [Loanno_MaxBalance_Count] query:
SELECT DISTINCT
[Property].Loanno,
IIf(Loanno_MaxBalance_Count.RowCount>1, 8, [Property].PropertyType) AS PropertyType
FROM
[Property]
INNER JOIN
[Loanno_MaxBalance_Count]
ON [Property].Loanno=Loanno_MaxBalance_Count.Loanno
AND [Property].[Balance amount]=Loanno_MaxBalance_Count.[Balance amount]
Step 3b: Gee, that's not too bad at all. Let's "go for it" and replace the [Loanno_MaxBalance_Count] query reference with its SQL code (from Step 2b) as a subquery:
SELECT DISTINCT
[Property].Loanno,
IIf(Loanno_MaxBalance_Count.RowCount>1, 8, [Property].PropertyType) AS PropertyType
FROM
[Property]
INNER JOIN
(
SELECT
[Property].Loanno,
[Property].[Balance amount],
COUNT(*) AS RowCount
FROM
[Property]
INNER JOIN
(
SELECT
Loanno,
MAX([Balance amount]) AS MaxBalance
FROM [Property]
GROUP BY Loanno
) AS Loanno_MaxBalance
ON Loanno_MaxBalance.Loanno=[Property].Loanno
AND Loanno_MaxBalance.MaxBalance=[Property].[Balance amount]
GROUP BY [Property].Loanno, [Property].[Balance amount]
) AS Loanno_MaxBalance_Count
ON [Property].Loanno=Loanno_MaxBalance_Count.Loanno
AND [Property].[Balance amount]=Loanno_MaxBalance_Count.[Balance amount]
That's it! One self-contained query with no need for saved Access query dependencies.