C# 并删除 SQL 服务器数据库中的特定行

Question

My problem is I don't get any errors, but when I tried to delete specific data from the database, the system would just display Data Deleted .

private void Delete_Click(object sender, EventArgs e)
{
    string Query = "delete from dbo.student where C_ID=" + textBox1.Text;
    cc.con = new SqlConnection(cs.DBConn);
    cc.con.Open();

    try
    {
        MessageBox.Show("Data Deleted");
    }
    catch
    {
        MessageBox.Show("User Not Deleted");
    }
}

Answer 1

You need to actually create a SqlCommand and execute the query, Also - to avoid SQL injection and other problems, please always use parametrized queries!

Try something like this:

private void Delete_Click(object sender, EventArgs e)
{
    string delQuery = "DELETE FROM dbo.student WHERE C_ID = @ID";

    try
    {
        using (SqlConnection conn = new SqlConnection(cs.DBConn))
        using (SqlCommand cmdDel = new SqlCommand(delQuery, conn))
        {
            // define parameter and set value
            cmdDel.Parameters.Add("@ID", SqlDbType.Int).Value = Convert.ToInt32(textBox1.Text);

            // open connection, execute query, close connection
            conn.Open();
            int rowsDeleted = cmdDel.ExecuteNonQuery();
            conn.Close();

            // show success message
            MessageBox.Show("Data Deleted");
        }
    }
    catch
    {
        MessageBox.Show("User Not Deleted");
    }
}