CODEWITHSUNDEEP
c#mysqldatabase
Reaven Smith
Reaven Smith

Reputation: 359

C# reading int from mysql

Having problem reading a value from my table in mysql, is the index value i cant read the value back no matter what. all i get is the initialized value of 0 i dont get any error because it return 0, if i run the query in the database it get the correct value. i tried to use executeScalar() but with the same result .

     MySqlConnection conn = new MySqlConnection(MyConString);
    ulong ukey=0;
            try
            {
                string sql_users2 = "SELECT `key` FROM `permuser` WHERE `user` = '" + myuser + "' AND `code` = '" + mycode + "'";
                MySqlCommand cmdSel2 = new MySqlCommand(sql_users2, conn);
                conn.Open();
                MySqlDataReader dr2 = cmdSel2.ExecuteReader();
                dr2.Read();

                    ukey = dr2.GetUInt64(dr2.GetOrdinal("key")); 
                   // MessageBox.Show("Sorry " + myuser + " already have access to " + mycode + ",\nIf this is an extension, search for the user which key is  " + ukey + "   and edit the end date.", "Duplicate User Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning);

                dr2.Close();
                dr2.Dispose();
            }
            catch (MySqlException ex) //catch 2
            {

                MessageBox.Show("catch ukey\nCan't connect to database\n" + ex.ToString());
            }

            conn.Close();
            conn.Dispose();

Upvotes: 0

Views: 6645

Answers (2)

Steve
Steve

Reputation: 216243

You are returning a single value from your query, so you could use directly ExecuteScalar instead of ExecuteReader. (the link point to the description for SqlServer, but it is the same for MySql)

An important question to never forget is the usage of parameters instead of string concatenation.
What happen if your myuser or mycode variables contain a single quote? You get wrong results or syntax errors. Of course, the main problem is the Sql Injection attack to never understimate.

using(MySqlConnection conn = new MySqlConnection(MyConString))
{
    ulong ukey=0;
    try
    {
        string sql_users2 = "SELECT `key` FROM `permuser` WHERE `user` = @usr AND `code` = @code";
        MySqlCommand cmdSel2 = new MySqlCommand(sql_users2, conn);
        conn.Open();
        cmdSel2.Parameters.AddWithValue("@usr", myuser);
        cmdSel2.Parameters.AddWithValue("@code", mycode);

        object result  = cmdSel2.ExecuteScalar();
        if(result != null)
            ukey = Convert.ToUInt64(result); 


    }
    catch (MySqlException ex) //catch 2
    {
        MessageBox.Show("catch ukey\nCan't connect to database\n" + ex.ToString());
    }
}

also I am a bit perplexed about your usage of UInt64. What kind of datatype is stored in the key column?

Upvotes: 1

devilkkw
devilkkw

Reputation: 438

way is many simply:

ukey = (uint)dr2[0];

Upvotes: 0

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