How to add identity column to datatable using c#

How to add identity column to datatable using c#. Im using Sql compact server.开发者_运维问答

You could try something like this maybe?

private void AddAutoIncrementColumn()
{
    DataColumn column = new DataColumn();
    column.DataType = System.Type.GetType("System.Int32");
    column.AutoIncrement = true;
    column.AutoIncrementSeed = 1000;
    column.AutoIncrementStep = 10;

    // Add the column to a new DataTable.
    DataTable table = new DataTable("table");
    table.Columns.Add(column);
}

 DataTable table = new DataTable("table");


DataColumn dc= table.Columns.Add("id", typeof(int));
        dc.AutoIncrement=true;
        dc.AutoIncrementSeed = 1;
        dc.AutoIncrementStep = 1;

// Add the new column name in DataTable

table.Columns.Add("name",typeof(string));

    table.Rows.Add(null, "A");
    table.Rows.Add(null, "B");
    table.Rows.Add(null, "C");

If the DataTable is already populated. you can use below method

void AddAndPopulateDataTableRowID(DataTable dt, string col, bool isGUID)
    {
        if(isGUID)
            dt.Columns.Add(col, typeof(System.Guid));
        else
            dt.Columns.Add(col, typeof(System.Int32));

        int rowid = 1;
        foreach (DataRow dr in dt.Rows)
        {
            if (isGUID)
                dr[col] = Guid.NewGuid();
            else
                dr[col] = rowid++;
        }

    }

You don't do autoincrement on DataTable (or front-end for that matter), unless you want to make your application a single user application only.

If you need the autoincrement, just do it in database, then retrieve the autoincremented id produced from database to your front-end.

See my answer here, just change the SqliteDataAdapter to SqlDataAdapter, SqliteConnection to SqlConnection, etc : anyway see why I get this "Concurrency Violation" in these few lines of code??? Concurrency violation: the UpdateCommand affected 0 of the expected 1 records

Just my two cents. Auto-increment is useful in a Winform app (stand alone as Michael Buen rightly said), i.e.:

DatagridView is being used to display data that does not have a "key field", the same can be used for enumeration.

I dont think its a good idea to use autoincrement on datatable if you are using insert and delete to a datatable because the number will not be rearranget, no final i will share a small idea how can we use autoincrement manual.

         DataTable dt = new DataTable();
        dt.Columns.Add("ID",typeof(int));
        dt.Columns.Add("Produto Nome", typeof(string));  

        dt.Rows.Add(null, "A");
        dt.Rows.Add(null, "B");
        dt.Rows.Add(null, "C");

        for(int i=0;i < dt.Rows.Count;i++)
        {
            dt.Rows[i]["ID"] = i + 1;
        }

always when finalizing the insert or delete must run this loop

         for(int i=0;i < dt.Rows.Count;i++)
        {
            dt.Rows[i]["ID"] = i + 1;
        }