Insert from Two tables to One while duplicates are ignored - sql

Question

I am trying to insert from two MS Access tables into one ms access table.
In one of the two tables there is a column that contains a duplicate value.
What I have at the moment is:
Dim MySQL As String = "INSERT INTO XML_TEST_CASE (" & _
"TCParmId, " & _
"TestCase, " & _
"MessageType, " & _
"FileNo, " & _
"InstructionNo, " & _
"TransactionNo, " & _
"ElementNo, " & _
"MessageSection, " & _
"ElementLevel, " & _
"FullElementPath, " & _
"ElementValue, " & _
"ElementValueNew, " & _
"NameSpace, " & _
"NameSpaceValue, " & _
"Attribute, " & _
"AttributeValue, " & _
"TestCaseDescription) " & _
"SELECT " & _
"P.TCParmId, " & _
"P.TestCase, " & _
"P.MessageType, " & _
"P.FileNo, " & _
"P.InstructionNo, " & _
"P.TransactionNo, " & _
"S.ElementNo, " & _
"S.MessageSection, " & _
"S.ElementLevel, " & _
"S.ElementPath + S.Element, " & _
"S.ElementValue, " & _
"S.ElementValue, " & _
"S.NameSpace, " & _
"S.NameSpaceValue, " & _
"S.Attribute, " & _
"S.AttributeValue, " & _
"P.TestCaseDescription " & _
"FROM XML_TEST_CASE_PARAMETER P, XML_MESSAGE_STRUCTURE S " & _
"WHERE S.MessageType = P.MessageType " & _
"AND P.TestCase = '" & MyTestCase & "' " & _
"AND P.MessageType = '" & MyMessageType & "' " & _
"AND P.FileNo = " & MyFileNo & " " & _
"AND P.InstructionNo = " & MyInstructionNo & " " & _
"AND P.TransactionNo = " & MyTransactionNo & ";"
The problem is that in the XML_MESSAGE_STRUCTURE table it happens that S.ElementNo sometimes appreas more than once which then cuasing that I get also more than one records in my destination table for the specific ElementNo. This I do not want.
Any help is appreaciated.
Rico

Answer 1

Instead of SELECT DISTINCT, you could group by all of the fields except ElementNo. For ElementNo, you would select Max(ElementNo):
Dim MySQL As String = "INSERT INTO XML_TEST_CASE (" & _
"TCParmId, " & _
"TestCase, " & _
"MessageType, " & _
"FileNo, " & _
"InstructionNo, " & _
"TransactionNo, " & _
"ElementNo, " & _
"MessageSection, " & _
...
"SELECT " & _
"P.TCParmId, " & _
"P.TestCase, " & _
"P.MessageType, " & _
"P.FileNo, " & _
"P.InstructionNo, " & _
"P.TransactionNo, " & _
"Max(S.ElementNo), " & _
"S.MessageSection, " & _
...
"FROM XML_TEST_CASE_PARAMETER P, XML_MESSAGE_STRUCTURE S " & _
"WHERE S.MessageType = P.MessageType " & _
"AND P.TestCase = '" & MyTestCase & "' " & _
"AND P.MessageType = '" & MyMessageType & "' " & _
"AND P.FileNo = " & MyFileNo & " " & _
"AND P.InstructionNo = " & MyInstructionNo & " " & _
"AND P.TransactionNo = " & MyTransactionNo & _
"GROUP BY " & _
"P.TCParmId, " & _
"P.TestCase, " & _
"P.MessageType, " & _
"P.FileNo, " & _
"P.InstructionNo, " & _
"P.TransactionNo, " & _
"S.MessageSection, " & _
...
";"