Dears

I would like to insert some records from table into another table, something like this command of SQL : Insert ito headerTable Select Column1,Sum(Column2),Max(Column3) From DetailTable Where Column2 > 100 Group by Column1

Remember that for performance reasons I cant use a loop in my developing language (c#) and I want to do it in manner like SQL commands. there can be thousands of records in the DetailTable and using a loop would be very very slow.

if your using MS SQL Server you can use the BulkInsert command. and MDSN search on BulkInsert .Net 2.0 should point you in the right direction. There have also been posts on these forums about it as well. In summary it would look something like this:

ResultSet fields = new ResultSet(3);
fields.DefineField(DetailTableFields.Column1, 0);
fields.DefineField(DetailTableFields.Column2, 1, AggregateFunction.Sum);
fields.DefineField(DetailTableFields.Column3, 2, AggregateFunction.Max);

IGroupByCollection grouping = new GroupByCollection();
grouping.Add(ableFields.Column1);

IPrediateExpression filter = new PredicateExpression(DetailTableFields.Column2 > 100);

DataTable results = new DataTable();
string cnn;
using(DataAccessAdatper adapter = new DataAccessAdatper())
{
     cnn = adapter.ConnectionString;
     adapter.FetchTypedList(fields, results, filter, 0, null, null, false, grouping);
}

using (SqlBulkCopy copy = new SqlBulkCopy(cnn))
{ 
    //begin sql transaction
    //configure field mappings and sql bulk copy options if necessary
    try
    {
         copy.DestinationTableName = "headerTable";
         copy.WriteToServer(table);

        //commit
      }
      catch
      {
         //rollback
      }
}

You may also use a stored Procedure and call it from LLBLGen Pro code.