ExecuteReader: Connection property has not been initailized

Question

The error with ExecuteReader: Connection property has not been initialized is giving me a fit. I think I have it set up right. I will show you how I create the mssql connection and then what I am requesting, and the class I created to read/write and open/close the connection. (Three different parts of the app but I just lumped them together so you could see the actual logic flow I hope.)

What am I missing, or where am I supposed to put the connection? Example? I appreciate the help!

Here is the using statement I start with:

using (MSSQL mssqldb = new MSSQL(Constants.msSqlServer, Constants.msSqlDb, Constants.msSqlUid, Constants.msSqlPswd))

Here is where I say "Hey, get me my data using my MSSQL class"

using (var results = mssqldb.Read("SELECT TOP 1 * FROM AlertLog ORDER BY AlarmID DESC"))
{
    results.Read();
    legacyAlert = Int32.Parse(results["AlarmId"].ToString().Trim());
}

Here is the MSSQL class

class MSSQL : IDisposable
{
    public MSSQL(string server, string database, string uid, string pswd)
    {
        string msSqlConnectionString = @"Data Source=" + server + ";Initial Catalog=" + database + ";user id=" + uid + ";password=" + pswd;

        SqlConnection msqlConnection = new SqlConnection(msSqlConnectionString);
        msqlConnection.Open();
        Console.WriteLine("MS SQL OPEN!");
    }

    public void Write(string sql)
    {
        using (SqlCommand myCommand = new SqlCommand(sql, msqlConnection))
        myCommand.ExecuteNonQuery();
    }

    public SqlDataReader Read(string sql)
    {
        using (SqlCommand myCommand = new SqlCommand(sql, msqlConnection))
        return myCommand.ExecuteReader();
    }

    public void Dispose()
    {
        try {
            msqlConnection.Close();
        }
        catch (SqlException ex) {
            Console.Error.WriteLine("MS SQL Error - Closing Database");
            Console.Error.WriteLine(ex);
        }
        msqlConnection.Dispose();
    }

    private SqlConnection msqlConnection;
}

A bit off-base, but you shouldn't create a single connection to the server like that. When you're done with the connection, it should be disposed of. — Duncan Finney
– Duncan Finney, Commented Jan 31, 2014 at 19:11
I had thought about that, but I use it everywhere in the app in multiple threads, so I decided to use it from the top. I understand what you are saying, but I thought it would save me multiple connection issues. — Chris
– Chris, Commented Jan 31, 2014 at 19:47
This sounds like all those "I thought string concatenation would save me multiple parameterization issues..." arguments that happen before a web site gets hacked with SQL injection... — Aaron Bertrand
– Aaron Bertrand, Commented Jan 31, 2014 at 19:54
This is getting off topic, there is a suggestion to an answer below, but I don't understand it. If anyone could possibly show me an example of what I am doing wrong, I would appreciate it. — Chris
– Chris, Commented Jan 31, 2014 at 19:58

SLaks · Accepted Answer · 2014-01-31 19:00:15Z

1

msqlConnection is null.

Your constructor creates a local variable named msqlConnection, but does not assign to the field.

answered Jan 31, 2014 at 19:00

SLaks

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2 Comments

Chris Over a year ago

Still learning programming, so please excuse my ignorance. I used exactly the same way for a mysql connection and that works, but i don't understand the assign to the field part that you mean.

Chris Over a year ago

OK, a big DUH... thanks I figured it out after it was staring me in the face for a few minutes.

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