Question

con.Open();
cmd = new OleDbCommand("UPDATE staff SET StaffNr = @a, FirstName = @b, 
    Surname = @c, Email = @d, Balance = @e WHERE Email = @d", con);

cmd.Parameters.AddWithValue("@b", textBoxStaffName.Text);
cmd.Parameters.AddWithValue("@c", textBoxStaffSur.Text);
cmd.Parameters.AddWithValue("@d", textBoxStaffE.Text);
cmd.Parameters.AddWithValue("@e", double.Parse(textBoxSatffBal.Text));
cmd.Parameters.AddWithValue("@a", int.Parse(textBoxStaffNr.Text));
cmd.ExecuteNonQuery();
con.Close();

由于某种原因没有更新数据库，但代码运行

Answer 1

OldDb使用?作为参数，而非@x。您必须按顺序添加参数。 AddWithValue中忽略该名称（此方法来自通用超类）

con.Open();
cmd = new OleDbCommand("Update staff set StaffNr = ?, FirstName = ?, 
    Surname = ?, Balance = ? Where Email = ?", con);

cmd.Parameters.AddWithValue("@a", int.Parse(textBoxStaffNr.Text));
cmd.Parameters.AddWithValue("@b", textBoxStaffName.Text);
cmd.Parameters.AddWithValue("@c", textBoxStaffSur.Text);
cmd.Parameters.AddWithValue("@e", double.Parse(textBoxSatffBal.Text));
cmd.Parameters.AddWithValue("@d", textBoxStaffE.Text);
cmd.ExecuteNonQuery();
con.Close();

Oledb更新sql语句示例

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