Does MS Access suppress primary key violations on Inserts?

I am in the process of re-writing an MS Access database to SQL server and have found an strange issue开发者_高级运维 in Access that I am hoping someone can help with.

I have a table let's call it 'Main' with a Primary Key on the Account that is indexed and doesn't allow for duplicates. Seems simple enough but my issue is occurring when data is getting Inserted.

My INSERT query is (the number of fields have been limited for brevity)

INSERT INTO Main (Account, SentDate, Amount)
SELECT C.Account, C.SentDate, C.Amount
FROM 
    (CALLS C LEFT JOIN Bals B ON C.Account = B.ACCT_ID) 
LEFT JOIN AggAnt A ON C.Account = A.Account

The issue is this, if I run the SELECT portion of my query I get 2365 records but when I run the INSERT I get 2364 records. So I did some checking and I found one Account is duplicated the difference between the records is the SentDate and the Amount. But Access is inserting only one of the records and not throwing any kind of error message or anything. There is nothing in the query that says select the most recent date, etc.

Sample Data:

Account    SentDate   Amount
12345678   8/1/2011   123.00
23456789   8/1/2011   45678.00
34567890   8/1/2011   7850.00
45678912   8/1/2011   635.00
45678912   5/1/2011   982.00
56789123   8/1/2011   2639.00

In the sample I have one account that is duplicated 45678912 when I run my INSERT, I get no errors and I get the record from 8/1/2011.

Why is Access not throwing an error when this violates the PK on the table? Is there some quirk in Access to select one record and just skip the other?

I am totally stumped by this issue so any help would be great.

How are you running the query? If you're using DoCmd.RunSQL, switch to using the .Execute method of a DAO database object, and use dbFailOnError.

Dim db As DAO.Database
Dim strInsert As String
strInsert = "your insert statement"
Set db = CurrentDb
db.Execute strInsert, dbFailOnError
Set db = Nothing

Edit: If Main is an ODBC link to a SQL Server table, I would examine the Errors Collection (DAO) after db.Execute strInsert, dbFailOnError

After HansUp pointing me in the direction of checking for SetWarnings = false. I found it buried in my code which is why there was no warning message about the records not being inserted due to primary key violations.

A word of caution would be to make sure you want these messages suppressed.

Is there some quirk in Access to [update] one record and just skip the other?

Yes, you can control this behaviour at the engine level (also at the recordset level if using OLE DB).

For OLE DB (e.g. ADO) the setting is Jet OLEDB:Global Partial Bulk Ops:

determines the behavior of the Jet database engine when SQL DML bulk operations fail. When set to allow partial completion of bulk operations, inconsistent changes can occur because operations on some records could succeed and others could fail. When set to allow no partial completion of bulk operations, all changes are rolled back if a single error occurs. The Jet OLEDB:Global Partial Bulk Ops property setting can be overridden on a per-Recordset basis by setting the Jet OLEDB:Partial Bulk Ops property in the Properties collection of a Recordset object.

Note the default is to allow no partial completion of bulk operations.