Setting primarykey on Dataset

Question

I am importing data from a csv file into a datagrid and set a primary key. I tried objDataset1.Tables[0].PrimaryKey = objDataset1.Tables[0].Columns[1]; But I get error CS0029: Cannot implicitly convert type 'System.Data.DataColumn' to 'System.Data.DataColumn[]'

miker · Answer

Try this: DataColumn[] myKey = new DataColumn[1]; myKey[0] = objDataset1.Tables[0].Columns[1]; objDataset1.Tables[0].PrimaryKey = myKey;

mibuyt · Answer

Hi, Glad you get it working. Sorry about the previous post, it's hard to visualize over here on your problems. Wish you good luck. If you have doubts, please post in the forums :) Cheers.

isu_compu_dude · Answer

Yes that lets the page display without an error! Now I can try and learn more about datasets/grids and methods. Thank you

mibuyt · Answer

Hi, Try this instead. Before: objDataset1.Tables[0].PrimaryKey = objDataset1.Tables[0].Columns[1]; After: objDataset1.Tables[0].PrimaryKey[0] = objDataset1.Tables[0].Columns[1]; It works here, but i am not that sure it will works in your application. Keep me updated. Cheers.

isu_compu_dude · Answer

I think maybe I can't ...but I will have to create a new dataset and then parse through the 2 other datasets to fill it in using something like this http://msdn.microsoft.com/library/en-us/cpref/html/frlrfsystemdatadatasetclassmergetopic.asp Maybe I am wrong...this is all still new to me

isu_compu_dude · Answer

Every example I see say DataColumn[] myKey = new DataColumn[1]; Doesnt this create a new column? I want to use the existing data. here is what I have tried to do... I am trying to merge and sort lines in the 2 csv files String sConnectionString1 = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:/inetpub/csvdata/" + ListBox1.SelectedItem.Text + ";Extended Properties='text;HDR=No;FMT=Delimited;'"; String sConnectionString2 = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:/inetpub/csvdata/" + ListBox3.SelectedItem.Text + ";Extended Properties='text;HDR=No;FMT=Delimited;'"; // Create connection object by using the preceding connection string. OleDbConnection objConn1 = new OleDbConnection(sConnectionString1); OleDbConnection objConn2 = new OleDbConnection(sConnectionString2); // Open connection with the database. objConn1.Open(); objConn2.Open(); // Create new OleDbCommand to return data from worksheet. OleDbCommand objCmdSelect1 = new OleDbCommand("SELECT * FROM " + ListBox2.SelectedItem.Text, objConn1); OleDbCommand objCmdSelect2 = new OleDbCommand("SELECT * FROM " + ListBox4.SelectedItem.Text, objConn2); // Create new OleDbDataAdapter that is used to build a DataSet based on the preceding SQL SELECT statement. OleDbDataAdapter objAdapter1 = new OleDbDataAdapter(); OleDbDataAdapter objAdapter2 = new OleDbDataAdapter(); // Pass the Select command to the adapter. objAdapter1.SelectCommand = objCmdSelect1; objAdapter2.SelectCommand = objCmdSelect2; // Create new DataSet to hold information from the worksheet. DataSet objDataset1 = new DataSet(); DataSet objDataset2 = new DataSet(); DataSet objDataset3 = new DataSet(); DataSet objDataset4 = new DataSet(); // Fill the DataSet with the information from the worksheet. objAdapter1.Fill(objDataset1); objAdapter2.Fill(objDataset2); //bind to dataview //DataView dv1 = objDataset1.Tables[0].DefaultView; //DataView dv2 = objDataset2.Tables[0].DefaultView; //set primary key //DataColumn[] pk1 = objDataset1.Tables[0].Columns[1]; //DataColumn[] pk2 = objDataset2.Tables[0].Columns[1]; objDataset1.Tables[0].PrimaryKey = objDataset1.Tables[0].Columns[1]; objDataset2.Tables[0].PrimaryKey = objDataset2.Tables[0].Columns[1]; objDataset3.Merge(objDataset1, false, MissingSchemaAction.Add); objDataset3.Merge(objDataset2, false, MissingSchemaAction.Add); // Bind data to DataGrid control. DataGrid1.DataSource = objDataset3.Tables[0].DefaultView; DataGrid1.DataBind(); // Clean up objects. objConn1.Close(); objConn2.Close();

mibuyt · Answer

Hi, You want to set primary key for datagrid or dataset? Anyway, below is an example. Datagrid ----------- private void SetPrimaryKeys(){ // Create a new DataTable and set two DataColumn objects as primary keys. DataTable myTable = new DataTable(); DataColumn[] keys = new DataColumn[2]; DataColumn myColumn; // Create column 1. myColumn = new DataColumn(); myColumn.DataType = System.Type.GetType("System.String"); myColumn.ColumnName= "FirstName"; // Add the column to the DataTable.Columns collection. myTable.Columns.Add(myColumn); // Add the column to the array. keys[0] = myColumn; // Create column 2 and add it to the array. myColumn = new DataColumn(); myColumn.DataType = System.Type.GetType("System.String"); myColumn.ColumnName = "LastName"; myTable.Columns.Add(myColumn); // Add the column to the array. keys[1] = myColumn; // Set the PrimaryKeys property to the array. myTable.PrimaryKey = keys; } Reference http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemdatadatatableclassprimarykeytopic.asp DataSet ---------- public static DataSet GetCustomerData(string dataSetName) { DataSet ds = new DataSet(dataSetName); SqlConnection conn = new SqlConnection("Data Source=localhost;Integrated Security=SSPI;Initial Catalog=Northwind"); SqlDataAdapter da = new SqlDataAdapter("SELECT CustomerID, CompanyName, ContactName FROM Customers", conn); conn.Open(); // configure the primary key da.FillSchema(ds, SchemaType.Source, "Customers"); da.Fill(ds); conn.Close(); return ds; } Hope it helps. Cheers.