SQLiteDataReader.read（）清空结果？

Question

I have a method in my C# class that calls a single result from an SQLite database. My database connection opens successfully, but after running breakpoints at different places, I noticed something odd. This is my code:

Dictionary<string, string> getResult(string id)
{
    dataConn.Open();
    SQLiteCommand comm = dataConn.CreateCommand();
    comm.CommandText = "SELECT * FROM [tableName] WHERE id='" + id + "'";
    SQLiteDataReader result = comm.ExecuteReader();
    Dictionary<string, string> resultDict = new Dictionary<string, string>();

    /*
    This doesn't work.
    while(result.Read())
    {
        resultDict.Add(result.GetName(0), result.GetString(0));
    }
    */

    result.Read();
    for (int i = 0; i < result.FieldCount; i++)
    {
        resultDict.Add(result.GetName(i), result.GetString(i));
    }
    result.Dispose();
    comm.Dispose();
    dataConn.Close();
    return resultDict;
}

I know that I can use SQLiteParameters instead of inline concatenation, but for some reason they were breaking my query.

In my first loop, if I place a breakpoint just before it starts, I can see that my query has returned a single result, exactly what I need. But, when I go into my loop, before I execute any code other than reader.Read() , VS2010 says "Enumeration yielded no results." but they were there moments before?

So, I tried the second loop. Executing reader.Read() , and then looping through returned fields. When I do that, VS2010 throws the error "No current row selected.".

I'm completely lost with this, I have no idea what's wrong, because the rest of my SQLite connections for other database files work fine. I've tested my query in SQLite Administrator , and my query executes perfectly fine. All I'm aiming for is to end up with a dictionary where the key is the name of the field, and the value is the result of said field. Any ideas on what's wrong? Or, is there a way I can make this code simpler, in the process of fixing it?

Answer 1

Solved. For some reason, using .GetString(0) or .GetString(i) was breaking it. However, when I turned it into .GetValue(0).ToString() it worked fine. I have no idea why this is the case, it's beyond me, but it works.

Answer 2

Its because GetValue(0) didn't return a string.

Casting it to a string allowed you to add it to the Dictionary<string,string> .

Answer 3

I had a similar problem, in my case the table was empty, and i was asking for MAX() of some collumn. I solved it by first checking that COUNT(*) is not 0.