Question

I have to update table on SQL Server but first i have to check for existing data in table so if data is there update it, if not make a new insert:

cmd_sql.CommandText = " SELECT BrDok as id_dok " +
                      " FROM ordersstavke " +
                      " WHERE SifParFil = '" + rw_mat["sifskl_kor"] + "'" +
                      " AND DokumentTip = '" + rw_mat["vrst_dok"] + "'";

MySqlDataAdapter sql_adapter = new MySqlDataAdapter(cmd_sql);
DataSet dt_dok = new DataSet("DOK_MAT_EXCHANGE");
sql_adapter.Fill(dt_dok);

if (dt_dok.Tables["DOK_MAT_EXCHANGE"].Rows.Count == 0)
{
   myQuery = " INSERT INTO ordersstavke (BrDok, DocumentTip, SifParFil) " +
             " VALUES ('" + rw_mat["brdok"] + "', '" +
                            rw_mat["vrst_dok"] + "', '" +
                            rw_mat["sifskl_kor"] + "')";
}
else
{
    UPDATE DATA
}

But I have an error in the code, the error is here if (dt_dok.Tables["DOK_MAT_EXCHANGE"].Rows.Count == 0)

Object reference not set to an instance of an object.

The problem is in this if statement…

Answer 1

Ok, thanks guys, I wrote it like this

if (ds_dok.Tables[0].Rows.Count <= 0)
                    {
                        myQuery = " INSERT INTO ordersstavke (BrDok, " +
                                  " SifParFil) " +
                                  " VALUES ('" + rw_mat["brdok"] + "', '" +
                                                 rw_mat["sifskl_kor"] + "')";
                    }
                    else if (ds_dok.Tables[0].Rows.Count >= 1)
                    {

                        myQuery = "UPDATE ordersstavke " +
                                  "SET BrDok = '" + rw_mat["brdok"] + "', " +
                                  "SifParFil = '" + rw_mat["sifskl_kor"] + "', " +
                                  "WHERE BrDok = " + ds_dok.Tables["ordersstavke"].Rows[0]["BrDok"].ToString() + "'";

                    }

But there is a small problem in the section update: s_dok.Tables[“ordersstavke”].Rows[0][“BrDok”].ToString(), here it give me that loving error : Object reference not set to an instance of an object.

Maybe the update on MySQL goes on different way, I’m referencing on example on sql server and there update goes differently