Asp.Net SQL Update Statement

问题

I have an Asp.net application on my page the user requests for a user to be removed. This then populates my 'Admin_TaskList' db.

An administrator then goes in the secure area of the site and enters the users name and clicks a button. Upon the confirmation, the user is then deleted from my 'Users' db (already got this working) but I want my 'Admin_TaskList' db 'Status' column to change from 'To Do' to 'Completed'.

As I sad I have the delete bit working but I am struggling updating my other table.

Snippet of code I have tried

conn.Open();
SqlCommand cmd2 = new SqlCommand("UPDATE FROM Admin_TaskList SET Status = 'Complete' WHERE Description = 'Remove User' AND Name = @Name", conn);
cmd2.Parameters.AddWithValue("@Name", txtRemoveUser.Text);
SqlDataReader rd2 = cmd2.ExecuteReader();
conn.Close();

Full code

public void btnRemoveConfirmYes_Click(object sender, EventArgs e)
        {
            string connection = ConfigurationManager.ConnectionStrings["PaydayLunchConnectionString1"].ConnectionString;
            SqlConnection conn = new SqlConnection(connection);

            conn.Open();
            SqlCommand cmd1 = new SqlCommand("DELETE FROM Users WHERE Name = @Name", conn);
            cmd1.Parameters.AddWithValue("@Name", txtRemoveUser.Text);
            SqlDataReader rd1 = cmd1.ExecuteReader();
            conn.Close();

            conn.Open();
            SqlCommand cmd2 = new SqlCommand("UPDATE FROM Admin_TaskList SET Status = 'Complete' WHERE Description = 'Remove User' AND Name = @Name", conn);
            cmd2.Parameters.AddWithValue("@Name", txtRemoveUser.Text);
            SqlDataReader rd2 = cmd2.ExecuteReader();
            conn.Close();

            txtRemoveUser.Text = "";
            Response.Redirect("/AdminSide/TaskList.aspx");
        }

回答1:

Instead of using a SqlDataReader to update a value use SqlCommand.ExecuteNonQuery:

int updated = cmd2.ExecuteNonQuery();

Remember that you need to use ExecuteNonQuery on commands that modify your data like Delete, Insert or Update.

MSDN:

You can use the ExecuteNonQuery to perform catalog operations (for example, querying the structure of a database or creating database objects such as tables), or to change the data in a database without using a DataSet by executing UPDATE, INSERT, or DELETE statements.

The complete method:

int deleted, updated;
string connection = ConfigurationManager.ConnectionStrings["PaydayLunchConnectionString1"].ConnectionString;

using (var conn = new SqlConnection(connection))
{
    conn.Open();
    string delSql = "DELETE FROM Users WHERE Name = @Name";
    using (var cmd = new SqlCommand(delSql, conn))
    {
        cmd.Parameters.Add("@Name", SqlDbType.NVarChar).Value = txtRemoveUser.Text;
        deleted = cmd.ExecuteNonQuery();
    }

    string updSql = @"UPDATE Admin_TaskList 
                      SET Status = 'Complete' 
                      WHERE Description = 'Remove User' 
                      AND Name = @Name";
    using (var cmd = new SqlCommand(updSql, conn))
    {
        cmd.Parameters.Add("@Name", SqlDbType.NVarChar).Value = txtRemoveUser.Text;
        updated = cmd.ExecuteNonQuery();
    }
}

来源：https://stackoverflow.com/questions/34357484/asp-net-sql-update-statement

标签

ASP.NET

sql-server

webforms