Oledb Update command | 易学教程

问题

I make a program that saves and update a data from the database, I can save and read data, I can also update but the problem is, I can't select the "ID" as the index, here is my sample code using "ID" as the index,

cmd = new OleDbCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "UPDATE Records SET FirstName = @firstname, LastName = @lastname, Age = @age, Address = @address, Course = @course WHERE [ID] = @id";
cmd.Parameters.AddWithValue("@id", int.Parse(label7.Text));
cmd.Parameters.AddWithValue("@firstname", textBox1.Text);
cmd.Parameters.AddWithValue("@lastname", textBox2.Text);
cmd.Parameters.AddWithValue("@age", textBox3.Text);
cmd.Parameters.AddWithValue("@address", textBox4.Text);
cmd.Parameters.AddWithValue("@course", textBox5.Text);
cmd.Connection = cn;
cn.Open();
cmd.ExecuteNonQuery();
{
    MessageBox.Show("Update Success!");
    cn.Close();
}

and here is my update code that works, but the index is the "firstname",

cmd = new OleDbCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "UPDATE Records SET FirstName = @firstname, LastName = @lastname, Age = @age, Address = @address, Course = @course WHERE FirstName = @firstname";
//cmd.Parameters.AddWithValue("@id", int.Parse(label7.Text));
cmd.Parameters.AddWithValue("@firstname", textBox1.Text);
cmd.Parameters.AddWithValue("@lastname", textBox2.Text);
cmd.Parameters.AddWithValue("@age", textBox3.Text);
cmd.Parameters.AddWithValue("@address", textBox4.Text);
cmd.Parameters.AddWithValue("@course", textBox5.Text);
cmd.Connection = cn;
cn.Open();
cmd.ExecuteNonQuery();
{
    MessageBox.Show("Update Success!");
    cn.Close();`
}

It works but the problem is I can't update the "FirstName", Is there a way that I can also update the Firstname? or use the "ID" as the index? thanks

回答1:

I don't know what database you are going against, however, I don't know if the OleDB is being picky on the ordinal sequence of your parameters. ie: Have you tried putting your "ID" parameter in the last position to match the actual order of the fields of your update command? I don't know if it's throwing it out.

回答2:

You should add the following code after the last line of ID:

cmd = new OleDbCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "UPDATE Records SET FirstName = @firstname, LastName = @lastname, Age = @age, Address = @address, Course = @course WHERE [ID] = @id";
cmd.Parameters.AddWithValue("@firstname", textBox1.Text);
cmd.Parameters.AddWithValue("@lastname", textBox2.Text);
cmd.Parameters.AddWithValue("@age", textBox3.Text);
cmd.Parameters.AddWithValue("@address", textBox4.Text);
cmd.Parameters.AddWithValue("@course", textBox5.Text);
cmd.Parameters.AddWithValue("@id", int.Parse(label7.Text));
cmd.Connection = cn;
cn.Open();
cmd.ExecuteNonQuery(); {
    MessageBox.Show("Update Success!");
    cn.Close();
}

来源：https://stackoverflow.com/questions/15126427/oledb-update-command

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oledb