I’m trying to learn how to connect to an SQL Server database (I’m using the AdventureWorks sample database), but I’m having problems.

Here’s the code I’m using:
Code: [Select]// define connection string for database server
string connectionString = "server=<server name>; database=AdventureWorks; uid=<user name>; pwd=;"; // no password

// define SqlConnection connection to database using connection string
SqlConnection conn = null;
try
{
conn = new SqlConnection (connectionString);
}
catch (Exception EXC)
{
MessageBox.Show (exc.Message, "conn = new SqlConnection (connectionString);");
}

// define SqlCommand command or command string that CONTAINS query
string commandString = "SELECT * from <table name>";

// define SqlDataAdapter data adapter using command string & connection object:
SqlDataAdapter dataAdapter = new SqlDataAdapter (commandString, conn);

// create new DataSet object (create DataSet)
DataSet ds = new DataSet ();

try
{ // fill dataset object with query result via data adapter (for SELECT)
dataAdapter.Fill (ds, "<table name>");
}
catch (Exception exc)
{
MessageBox.Show (exc.Message, "dataAdapter.Fill (ds, \"<table name>\");");
}

// result of query now stored in dataset object in table "<table name>"
// get reference to table by using indexer property of dataset object's Tables collection
dataTable = ds.Tables ["<table name>"];At the statement
Code: [Select]dataAdapter.Fill (ds, "<table name>");
I'm getting the FOLLOWING error: "Login failed for user ''."

As near as I can make out, the database AdventureWorks that I see in SQL Server 2008 Management Studio and that I'm trying to access resides at either C:\Program Files\Microsoft SQL Server\100\Tools\Samples\AdventureWorks 2008 OLTP or
C:\Program Files\Microsoft SQL Server\100\Tools\Samples\AdventureWorks OLTP.
I thought that maybe the problem was I was supposed to specify the full path name in the connection string, but that didn't help. Any suggestions?

NOWHERE do I see a provider name (should probably be SQLNCLI10). The providers are the low level component instructions from MDAC which are needed to do the actual I/O into the database.

Check out this page for more assistance.

Good luck.