Question: I am learning with this so bear with me...I am trying to create the DB object to access the table.

```
AppDatabaseDataContext appDb = new AppDatabaseDataContext();

```

This gives me an error, so I create the constructor...

```
public AppDatabaseDataContext()
{

} 

```

Now this tells me that `System.Data.Linq.DataContext` does not contain a constructor that takes 0 parameters. Why? 

Thanks!

Answer: 
You need to specify a connection string. If you know it's always going to be the same (for example, localhost) you can just hard-code it in your parameterless constructor:

```
public AppDatabaseDataContext()
    : this(@"Data Source=localhost;Initial Catalog=Foo;Integrated Security=True")
{
}

```

Notice how we chain the constructor to call the version that consumes a connection string. This way, you can instantiate the data context using the parameterless constructor, and it will use this default connection string.
```
Just Change your connection string just like  
<connectionStrings>
    <add name="DBLabConnectionString" 
         connectionString="Data Source=.\SQLExpress;Initial Catalog=DatabaseName;
         Integrated Security=True" 
         providerName="System.Data.SqlClient" />
 </connectionStrings>

```