Unable to connect to a Local Database

Question

I am playing with C# and a local database (An empty SQL Server Compact Edition database for local data)

But I am unable to connect to the database and get data.

This is what I try:

// Properties.Settings.Default.DatabaseConnectionString = Data Source=|DataDirectory|\Database.sdf
// I guess Visual Studio put it there after I created my database...

using(SqlConnection sqlConnection = new SqlConnection(Properties.Settings.Default.DatabaseConnectionString)) {
    using(SqlCommand sqlCommand = new SqlCommand("SELECT * FROM users WHERE id = @id", sqlConnection)) {
        sqlCommand.CommandType = CommandType.StoredProcedure;
        sqlCommand.Parameters.AddWithValue("@id", 1);
        try {
            sqlConnection.Open();
            SqlDataReader reader = sqlCommand.ExecuteReader(CommandBehavior.SingleRow);
            if(reader.Read()) {
                System.Console.WriteLine(reader);
                System.Console.WriteLine(reader["id"]);
                System.Console.WriteLine(reader["name"]);
            }
        }
        catch(Exception e) {
            System.Console.WriteLine(e.GetBaseException());
        }
        finally {
            sqlConnection.Close();
        }
    }
}

My whole programm hangs for a while, after the pause I get this message:

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

Answer 1

I am playing with C# and a local database (An empty SQL Server Compact Edition database for local data)

You are using a Sql Server Compact file, not a Sql Server Local DB

To deal with Sql Server Compact, you need to use the System.Data.SqlServerCe namespace, not System.Data.SqlServer.

Replace SqlConnection, SqlCommand, ...

With SqlceConnection, SqlCeCommand, ...

---

And Stored procedures are not supported in Sql Server Compact (How to use Stored Procedure in SqlCE), so sqlCeCommand.CommandType can not be CommandType.StoredProcedure.

You need to use commandType.Text with command parameters.

using(SqlCeConnection sqlCeConnection = new SqlCeConnection(Properties.Settings.Default.DatabaseConnectionString)) {
    using(SqlCeCommand sqlCeCommand = new SqlCeCommand("SELECT * FROM users WHERE id = @id", sqlCeConnection)) {
        sqlCeCommand.CommandType = CommandType.Text;
        sqlCeCommand.Parameters.AddWithValue("@id", 1);
        try {
            sqlCeConnection.Open();
            SqlCeDataReader reader = sqlCeCommand.ExecuteReader(CommandBehavior.SingleRow);
            if(reader.Read()) {
                System.Console.WriteLine(reader);
                System.Console.WriteLine(reader["id"]);
                System.Console.WriteLine(reader["name"]);
            }
        }
        catch(Exception e) {
            System.Console.WriteLine(e.GetBaseException());
        }
        finally {
            sqlCeConnection.Close();
        }
    }
}

Answer 2

You need to use:

using System.Data.SqlServerCe;

And then

using (SqlCeConnection sqlConnection = new SqlCeConnection(Properties.Settings.Default.DatabaseConnectionString))
{
    using (SqlCeCommand sqlCommand = new SqlCeCommand("SELECT * FROM users WHERE id = @id", sqlConnection))
    {
        sqlCommand.CommandType = CommandType.Text;
        sqlCommand.Parameters.AddWithValue("@id", 1);
        try
        {
            sqlConnection.Open();
            SqlCeDataReader reader = sqlCommand.ExecuteReader(CommandBehavior.SingleRow);
            if (reader.Read())
            {
                System.Console.WriteLine(reader);
                System.Console.WriteLine(reader["id"]);
                System.Console.WriteLine(reader["name"]);
            }
        }
        catch (Exception e)
        {
            System.Console.WriteLine(e.GetBaseException());
        }
        finally
        {
            sqlConnection.Close();
        }
    }
}