How do I prevent primary key violation when updating an access database

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I can successfully import two tables from a paradox database and and add the the data into one access table.From the one paradox table I use the ID field as it is the primary key to link clockings to dates and I made my access primary key equal to the ID field of the Clockd.ID.

How do I append the access table when updating from the paradox database adding just new records
I am a little bit stumped on this
This is how far I have gotten.Any guidance would be appreciated

C#

private void mtrBtnLoad_Click(object sender, EventArgs e)
{
   string connStringSource = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=c:\\Program Files\\Supertime\\db;Extended Properties=Paradox 5.x;";

   string connStringDest = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Users\\Yellow\\Documents\\paradoxExport.accdb; Persist Security Info=False;";

   OleDbConnection connSource = new OleDbConnection(connStringSource);
   OleDbConnection connDest = new OleDbConnection(connStringDest);

   OleDbCommand cmdSelect = new OleDbCommand(@"Select Clockd.ID, Empmas.EmpNo, Empmas.Name, Clockd.DateTime, Calc0R1, Calc1R1, Calc2R1, Calc3R1, Calc4R1, TotalHours, Target0R1 FROM Empmas INNER JOIN Clockd ON Empmas.EmpNo=Clockd.Empno", connSource);

   OleDbCommand cmdIns = new OleDbCommand(@"INSERT INTO Clockd ([ID], EmpNo, [Name], [DateTime], Calc0R1, Calc1R1, Calc2R1, Calc3R1, Calc4R1, TotalHours, Target0R1) VALUES (@ID, @EmpNo, @Name, @DateTime, @Calc0R1, @Calc1R1, @Calc2R1, @Calc3R1, @Calc4R1, @TotalHours, @Target0R1)", connDest);

   cmdIns.Parameters.Add(new OleDbParameter("@ID", OleDbType.VarChar, 11,"ID"));
   cmdIns.Parameters.Add(new OleDbParameter("@EmpNo", OleDbType.VarChar, 11, "EmpNo"));
   cmdIns.Parameters.Add(new OleDbParameter("@Name", OleDbType.VarChar, 11, "Name"));
   cmdIns.Parameters.Add(new OleDbParameter("@DateTime", OleDbType.Date, 4, "DateTime"));
   cmdIns.Parameters.Add(new OleDbParameter("@Calc0R1", OleDbType.Integer, 8, "Calc0R1"));
   cmdIns.Parameters.Add(new OleDbParameter("@Calc1R1", OleDbType.Integer,8, "Calc1R1"));
   cmdIns.Parameters.Add(new OleDbParameter("@Calc2R1", OleDbType.Integer, 8, "Calc2R1"));
   cmdIns.Parameters.Add(new OleDbParameter("@Calc3R1", OleDbType.Integer, 8, "Calc3R1"));
   cmdIns.Parameters.Add(new OleDbParameter("@Calc4R1", OleDbType.Integer, 8, "Calc4R1"));
   cmdIns.Parameters.Add(new OleDbParameter("@TotalHours", OleDbType.Integer, 4, "TotalHours"));
   cmdIns.Parameters.Add(new OleDbParameter("@Target0R1", OleDbType.Integer, 4, "Target0R1"));

   OleDbDataAdapter da = new OleDbDataAdapter(connStringDest,connStringDest); 
   da.AcceptChangesDuringFill = false;
   da.SelectCommand = cmdSelect;
   da.InsertCommand = cmdIns;

   System.Data.DataSet ds = new System.Data.DataSet();
   da.Fill(ds);
   da.Update(ds);
   DataTable dt = new DataTable();
   BindingSource bs = new BindingSource();
   bs.DataSource = dt;
   dvg1.DataSource = bs;
}

Posted 20-Mar-15 20:32pm

Gerhard_Louis

Updated 20-Mar-15 22:56pm

phil.o

v2

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Member 11428137 · Accepted Answer · 2015-03-20T23:31:00

You'll need to get your insert query to check if the ID exists already before inserting the record.
Unfortunately to be able to put a WHERE clause into an INSERT query in Access requires that you use an INSERT INTO SELECT query.
This of course means that you need to have a table to select from, whereas you want to just give it some values to insert.
This makes the query a little bit longer and not quite as clear as it would be with something like SQL Server, but should still be possible.

Give this insert query a try:

C#

OleDbCommand cmdIns = new OleDbCommand(@"INSERT INTO Clockd ([ID], EmpNo, [Name], [DateTime], Calc0R1, Calc1R1, Calc2R1, Calc3R1, Calc4R1, TotalHours, Target0R1) SELECT TOP 1 @ID, @EmpNo, @Name, @DateTime, @Calc0R1, @Calc1R1, @Calc2R1, @Calc3R1, @Calc4R1, @TotalHours, @Target0R1 FROM Clockd WHERE NOT EXISTS (SELECT [ID] FROM Clockd WHERE [ID]=@ID)", connDest);

It does a select (limited to 1 row) that will return all the parameters, but only if the ID doesn't already exist in the table.