ch 12-14 Databases

AlanWheeler · February 20th, 2014, 05:46 PM

Hi Imar,

The book teaches us how to use SQL Data Sources and Entity Framework Sources. Clearly you needed to teach both methods, but having learned them, I'd now like to ask for some perspective on these data sources.

(1) In the book project, ultimately EF also connects to SQL (there is a SQL connection string embedded in the "...Entities connection string" element in web.config). Does it have to? Can EF setup 'by itself' within VS?

(2) In practice is there any reason we would need to have both methods in use? If so, why would that be? If not, then is the Entity Framework the superior choice? It seems as though anything that can be done using SQL Data Sources can be accomplished through the EF Data Sources as well. Is that correct, or are there some subtle issues that might cause one to retain both methods in a given project? As I continue to review each aspect of the project site I see that the Providers use the 'standard' SQL connection string. Can they use the EF connection, or is that forbidden?

(3) Also, in the book, we connected to SQL first before we setup for EF operations ( Fig 14-2, we needed the SQL connection string). If the SQL connection had not already been present, how would we have connected/setup the EF without having first setup SQL?

(4) On a more specific note, if we use the ListView and want to have full CRUD operations, are we committed to having to delete in markup the columns we don't want to display? I also ran into a problem where I had deleted several columns in the markup, but the grid display seemed to be 'hanging on' to a 1-2 pixel width column for each of the deleted fields that looked weird. Is there a proscribed way to eliminate totally the columns you don't want to display in the ListView?

Thanks.

Best Regards,
Alan

madona321 · February 20th, 2014, 08:16 PM

On a more specific note, if we use the ListView and want to have full CRUD operations, are we committed to having to delete in markup the columns we don't want to display? I also ran into a problem where I had deleted several columns in the markup, but the grid display seemed to be 'hanging on' to a 1-2 pixel width column for each of the deleted fields that looked weird. Is there a proscribed way to eliminate totally the columns you don't want to display in the ListView?

Imar · February 21st, 2014, 02:30 PM

Hi Alan,

Quote:

(1) In the book project, ultimately EF also connects to SQL (there is a SQL connection string embedded in the "...Entities connection string" element in web.config). Does it have to? Can EF setup 'by itself' within VS?

EF can target other databases as well, but not "by itself"; it always targets a database. See here for more info: http://stackoverflow.com/questions/1...ious-databases

Quote:

(2) In practice is there any reason we would need to have both methods in use? If so, why would that be? If not, then is the Entity Framework the superior choice? It seems as though anything that can be done using SQL Data Sources can be accomplished through the EF Data Sources as well.

It's a matter of choice and preference. The SqlDataSource is easier to use at first, but harder to maintain in the long run. EF is a bit more complicated to learn, but more powerful.

Quote:

Can they use the EF connection, or is that forbidden?

Nope, that doesn't work. EF uses its own format with a traditional connection string embedded in its own connection string.

Quote:

(3) Also, in the book, we connected to SQL first before we setup for EF operations ( Fig 14-2, we needed the SQL connection string). If the SQL connection had not already been present, how would we have connected/setup the EF without having first setup SQL?

Yes, you'll get a dialog to create a connection.

Quote:

(4) On a more specific note, if we use the ListView and want to have full CRUD operations, are we committed to having to delete in markup the columns we don't want to display? I also ran into a problem where I had deleted several columns in the markup, but the grid display seemed to be 'hanging on' to a 1-2 pixel width column for each of the deleted fields that looked weird. Is there a proscribed way to eliminate totally the columns you don't want to display in the ListView?

That doesn't sound right. Deleting the fields should remove them completely. Maybe there was whitespace between the various elements in the template?

Cheers,

Imar