更新SQL Server时出错

Question

I get an error when l try to update my table. The table consist of 6 columns which l display in a data grid view on the windows form. The ID column is displayed in a label on the form to prevent users from editing.

Now when l try to update I get this error:

The multi-part identifier "lblId.Text" could not be bound.

Any suggestions will be helpful.

Here is my update code:

private void btnupdate_Click(object sender, EventArgs e)
{
    cn.Open();

    cmd = new SqlCommand ("UPDATE jimmy SET Id=@Id, 
         FirstName=@FirstName, LastName=@LastName, Telephone=@Telephone, 
        Address=@Address, City=@City,Country=@Country WHERE @Id=lblId.Text", cn);

    cmd.Parameters.AddWithValue("@Id", lblID.Text);
    cmd.Parameters.AddWithValue("@FirstName", txtfirstname.Text);
    cmd.Parameters.AddWithValue("@LastName", txtlastname.Text);
    cmd.Parameters.AddWithValue("@Telephone", txttelephone.Text);
    cmd.Parameters.AddWithValue("@Address", txtaddress.Text);
    cmd.Parameters.AddWithValue("@City", txtcity.Text);
    cmd.Parameters.AddWithValue("@Country", txtcountry.Text);

    cmd.ExecuteNonQuery();
    cn.Close();

    MessageBox.Show("Updated");
    cleartext();
}

Answer 1

The error came from your SQL command text at the WHERE clause.

It should be

WHERE Id = @Id

Instead of

WHERE @Id = lblId.Text 

You can't say to SQL Server to read a text from your textbox controller by putting lblId.Text directly into the SQL Command text.

Answer 2

WHERE @Id=lblId.Text应该在WHERE Id=@Id因为lblId.Text最有可能是您要作为参数值传递的UI控件值，无论如何您都说cmd.Parameters.AddWithValue("@Id", lblID.Text);