inserting and deleting not happening in local database (.sdf)

When I try to select values from a local database it executes without any issue. But when I try to insert and delete it's executing the query but it's not affecting any rows.

This is the code I'm using to delete row from my local database:

        SqlCeConnection sqlConnection1 = new SqlCeConnection();
        sqlConnection1.ConnectionString = "Data Source = Database1.sdf";

        SqlCeCommand cmd = sqlConnection1.CreateCommand();
        cmd.CommandType = System.Data.CommandType.Text;
        cmd.CommandText = "DELETE FROM table1 WHERE slno=2";
        cmd.Connection = sqlConnection1;

        sqlConnection1.Open();
        cmd.Prepare();
开发者_运维百科        int aff=cmd.ExecuteNonQuery();//here its returning '0'
        MessageBox.Show(aff.ToString());
        sqlConnection1.Dispose();
        sqlConnection1.Close();

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It is possible that the delete won't affect any rows.

As an aside, I would advise using the using statement in your code:

using (SqlCeConnection conn = new SqlCeConnection("Data Source = Database1.sdf"))
using (SqlCeCommand comm = new SqlCeCommand("DELETE FROM table1 WHERE slno = 2", conn))
{
    conn.Open();
    comm.CommandType = CommandType.Text;
    comm.ExecuteNonQuery();
}

This will handle disposal of relevant objects for you.

Assuming that the SQL is relevant to your database and that you have successfully connected using the connection string beforehand, then the above could will perform a delete action against your database.