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Question

protected DataTable GetData(string Query)
{
          DataTable data = new DataTable();
          try
          {
                strConnectionString = "data source=(local);Integrated Security=True;initial catalog=ps_erdb;";
                string Query = "Select ErdbBuildNumbereMinor from DBVersion";
                using (sqlConnection = new SqlConnection(strConnectionString))
                {
                    sqlConnection.Open();
                    SqlCommand cmd = sqlConnection.CreateCommand();
                    cmd.CommandTimeout = intConnectionTimeout;
                    cmd.CommandText = Query;
                    data.Load(cmd.ExecuteReader());
                    sqlConnection.Close();
                }
                return data;
            }
            catch (Exception ex)
            {
        }
        return data;
}

the above code returns a error

Cannot open database "ps_erdb" requested by the login. The login failed. Login failed for user 'MIG3-ESVTB\\HPSInstall'.

But when i manually open SQL Server Management Studio with above login ,i was able to connect to database and execute the query.

Answer 1

A few possibilities to look into:

1. What user were you logged in with on your local client? Your connection string indicates you're using integrated security so the application will present your current logged in credentials to SQL Server. To help diagnose, make sure you enable login auditing for both failed & successful logins. When you connect from SSMS and run SELECT suser_name(), what does it return?

2. Is the database set for multi_user mode (default) or single_user mode? Someone may have changed it to single_user. This allows the first and only one connection. All subsequent attempts will fail. If it's in single user mode, just run ALTER DATABASE ps_erdb SET MULTI_USER from SSMS

3. When you login via SSMS, were you able to query data from the ps_erdb database? If not, make sure you have a database user mapped to the 'MIG3-ESVTB\\HPSInstall' login and the appropriate permissions granted to the user (not the login).