can't manually update a mysql database containing text fields with c#

Question

I'm struggling with the problem of updating a MySQL database using a Windows Forms app. The code looks like this:

global_data.MyDA.UpdateCommand = new MySqlCommand("UPDATE words SET word = @word WHERE id = @id", global_data.connection);
global_data.MyDA.UpdateCommand.Parameters.Add(
    new MySqlParameter("@word", MySqlDbType.Text, 0x7FFF, ParameterDirection.Input, false,
    0, 0, "word", DataRowVersion.Proposed, (object)edtWord.Text));
global_data.MyDA.UpdateCommand.Parameters.Add(
    new MySqlParameter("@id", MySqlDbType.UInt32, 10, ParameterDirection.Input, false,
    0, 0, "id", DataRowVersion.Proposed, (object)current_id)); 
global_data.MyDA.Update(table);

However, it fails to update anything (in this case - replacing a string value with edtWord.Text ).
Could anyone help? Thanks!

Answer 1

Seems that you are trying to update the backend database with changes in the table object. That's fine for the Update method of a DataAdapter and when the table is binded to some UI control (a DataGridView for example) that changes its underlying datasource.

But if you have a simple unbound textbox and you want to update a record in the database the correct approach is to define a command and execute it

string cmdText = "UPDATE words SET word = @word WHERE id = @id";
using(MySqlConnection cn = new MySqlConnection(constring))
using(MySqlCommand cmd = new MySqlCommand(cmdText, cn))
{
    cn.Open();
    cmd.Parameters.AddWithValue("@word", edtWord.Text);
    cmd.Parameters.AddWithValue("@id", current_id);
    cmd.ExecuteNonQuery();
}

Note I have simplified the Parameter syntax for the sake of readability, not to imply that your code is wrong