NullReferenceException when connection to ASP.NET website
Posted by: John Lace
Date: January 03, 2010 02:08PM

Hello everyone. Firstly can I say I am very new to MySQL, in fact this is the first project I have ever used it in. I am getting an infuriating error when trying to get data from a MySQL table. Here is my code:

string strConnectionString = "Driver={MySQL ODBC 5.1 Driver}; Server=localhost;Database=myDB; Uid=root; Pwd=pw;";

using (OdbcConnection conn = new OdbcConnection(strConnectionString))

string strSQL = "SELECT ID, Name, ParentID, Active FROM Category WHERE (ParentID = -1);";

using (OdbcCommand cmd = new OdbcCommand(strSQL, conn))
using (OdbcDataReader dr = cmd.ExecuteReader())
while (dr.Read())
int intID = Convert.ToInt32(dr["ID"]);
string strName = Convert.ToString(dr["Name"]);
int intParentID = Convert.ToInt32(dr["ParentID"]);
bool blnActive = Convert.ToBoolean(dr["Active"]);

I get a NullReferenceException on the line "int intID = Convert.ToInt32(dr["ID"]);". The same thing happens if I try to get data from any other table. I can create a command and execute it and instantiate an OdbcDataReader which will contain the correct number of columns and will have "dr.HadRows" set to true but as soon as I try to access a data item from it I get a NullReferenceException. The stack trace is:

at System.Data.Odbc.OdbcConnection.get_ProviderInfo()
at System.Data.Odbc.OdbcConnection.get_IsV3Driver()
at System.Data.Odbc.OdbcDataReader.GetColAttributeStr(Int32 i, SQL_DESC v3FieldId, SQL_COLUMN v2FieldId, HANDLER handler)
at System.Data.Odbc.OdbcDataReader.GetName(Int32 i)
at System.Data.ProviderBase.FieldNameLookup..ctor(IDataReader reader, Int32 defaultLocaleID)
at System.Data.Odbc.OdbcDataReader.GetOrdinal(String value)
at System.Data.Odbc.OdbcDataReader.get_Item(String value)

I've tried googling "System.Data.Odbc.OdbcConnection.get_ProviderInfo()" and it returns no results. I know that there is nothing wrong with the connection string because if I use the same one and try to insert data it works fine. Can anyone help?

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NullReferenceException when connection to ASP.NET website
January 03, 2010 02:08PM

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