How to solve the connection when the login failed during C# programming in database?

Question

I did some coding on connecting data using Azure database on Windows Form and when I tried to retrieve the data, I received the following error:

An unhandled exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll.

Also in addition, I received a Login failed for user ''. When I tried to retrieve the data and located at myConnection.Open();

private void btnRetrieve_Click(object sender, EventArgs e)
{
    //Create a connection calling the App.config
    string conn = ConfigurationManager.ConnectionStrings["NYPConnection"].ConnectionString;
    //The query to use
    string query = "SELECT * FROM Users";
    SqlConnection myconnection = new SqlConnection(conn);
    //Create a Data Adapter
    SqlDataAdapter dadapter = new SqlDataAdapter(query, myconnection);
    //Create the dataset
    DataSet ds = new DataSet();

    //Open the connection
    ******myconnection.Open();******

    //Fill the Data Adapter
    dadapter.Fill(ds, "Users");
    myconnection.Close();
    //Bind the datagridview with the data set
    dataGridView1.DataSource = ds;
    dataGridView1.DataMember = "Users";
}

It appears that the database user credentials in the connection string is not correct. — Vivek N
– Vivek N, Commented Feb 25, 2016 at 3:26
Perhaps the answer to this question will solve your problem? stackoverflow.com/questions/24510804/… — Jim Mischel
– Jim Mischel, Commented Feb 25, 2016 at 3:26

Jens Meinecke · Accepted Answer · 2016-02-25 04:04:18Z

1

Print out the value of conn, using the following code:

string conn = ConfigurationManager.ConnectionStrings["NYPConnection"].ConnectionString;
Debug.WriteLine("conn= " + conn);

Have a look in the output window and you will probably find that conn is set to an empty string or maybe does not have the user name specified.

answered Feb 25, 2016 at 4:04

Jens Meinecke

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