DLinq

[Senna]

Hi

Have a question about DLinq.

The example code floating around looks like this:

Northwind db = new Northwind(@"C:\...\northwnd.mdf");
var custs = from c in db.Customers where c.City == "London" select c;

How does this work. Will it retreive all the rows from the Customer table
and then filter and select. Or does it generate a sql on the fly which will
return only the proper rows.

Or am I getting it all wrong.

[Richard Blewett [DevelopMentor]]

The filtering is performed on the server in this case

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

Hi

Have a question about DLinq.

The example code floating around looks like this:

Northwind db = new Northwind(@"C:\...\northwnd.mdf");
var custs = from c in db.Customers where c.City == "London" select c;

How does this work. Will it retreive all the rows from the Customer table
and then filter and select. Or does it generate a sql on the fly which will
return only the proper rows.

Or am I getting it all wrong.

[Senna]

Won't that be a performance hit for large amount of data. What if the
Customers table contains one million rows, these have to be sent over the
network and after the filtering is done it may onlybe 50 rows left that are
any use.

"Richard Blewett [DevelopMentor]" wrote:

The filtering is performed on the server in this case

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

Hi

Have a question about DLinq.

The example code floating around looks like this:

Northwind db = new Northwind(@"C:\...\northwnd.mdf");
var custs = from c in db.Customers where c.City == "London" select c;

How does this work. Will it retreive all the rows from the Customer table
and then filter and select. Or does it generate a sql on the fly which will
return only the proper rows.

Or am I getting it all wrong.

[Richard Blewett [DevelopMentor]]

No, quite the opposite. The data already exists in the database and its using standard database functionality to extract only the data that matches the filter. The alternative would be to bring the one million rows back to the client and filter them there which would be a nightmare scenario in terms of network traffic and client processing required

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

nntp://news.microsoft.com/microsoft.public.dotnet.languages.csharp/<38**********************************@microsoft.co m>

Won't that be a performance hit for large amount of data. What if the
Customers table contains one million rows, these have to be sent over the
network and after the filtering is done it may onlybe 50 rows left that are
any use.

"Richard Blewett [DevelopMentor]" wrote:

The filtering is performed on the server in this case

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

Hi

Have a question about DLinq.

The example code floating around looks like this:

Northwind db = new Northwind(@"C:\...\northwnd.mdf");
var custs = from c in db.Customers where c.City == "London" select c;

How does this work. Will it retreive all the rows from the Customer table
and then filter and select. Or does it generate a sql on the fly which will
return only the proper rows.

Or am I getting it all wrong.

[microsoft.public.dotnet.languages.csharp]

[Senna]

Ok, so
from c in db.Customers where c.City == "London" select c
does create a sql on the fly. Good to know.

Thanks for your answers.

"Richard Blewett [DevelopMentor]" wrote:

No, quite the opposite. The data already exists in the database and its using standard database functionality to extract only the data that matches the filter. The alternative would be to bring the one million rows back to the client and filter them there which would be a nightmare scenario in terms of network traffic and client processing required

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

nntp://news.microsoft.com/microsoft.public.dotnet.languages.csharp/<38**********************************@microsoft.co m>

Won't that be a performance hit for large amount of data. What if the
Customers table contains one million rows, these have to be sent over the
network and after the filtering is done it may onlybe 50 rows left that are
any use.

"Richard Blewett [DevelopMentor]" wrote:

> The filtering is performed on the server in this case
>
> Regards
>
> Richard Blewett - DevelopMentor
> http://www.dotnetconsult.co.uk/weblog
> http://www.dotnetconsult.co.uk
>
> Hi
>
> Have a question about DLinq.
>
> The example code floating around looks like this:
>
> Northwind db = new Northwind(@"C:\...\northwnd.mdf");
> var custs = from c in db.Customers where c.City == "London" select c;
>
> How does this work. Will it retreive all the rows from the Customer table
> and then filter and select. Or does it generate a sql on the fly which will
> return only the proper rows.
>
> Or am I getting it all wrong.
>
>

[microsoft.public.dotnet.languages.csharp]

[jeremiah johnson]

It creates SQL, but not like you're thinking. note that the FROM clause
is before the SELECT clause. Think of it as a collection of objects,
that you query, not a database. That's the point of dlinq.

watch this video: http://channel9.msdn.com/Showpost.aspx?postid=114680

dlinq is much more powerful than SQL+DataBase.

jeremiah

Senna wrote:

Ok, so
from c in db.Customers where c.City == "London" select c
does create a sql on the fly. Good to know.

Thanks for your answers.

"Richard Blewett [DevelopMentor]" wrote:

No, quite the opposite. The data already exists in the database and its using standard database functionality to extract only the data that matches the filter. The alternative would be to bring the one million rows back to the client and filter them there which would be a nightmare scenario in terms of network traffic and client processing required

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

nntp://news.microsoft.com/microsoft.public.dotnet.languages.csharp/<38**********************************@microsoft.co m>

Won't that be a performance hit for large amount of data. What if the
Customers table contains one million rows, these have to be sent over the
network and after the filtering is done it may onlybe 50 rows left that are
any use.

"Richard Blewett [DevelopMentor]" wrote:

> The filtering is performed on the server in this case
>
> Regards
>
> Richard Blewett - DevelopMentor
> http://www.dotnetconsult.co.uk/weblog
> http://www.dotnetconsult.co.uk
>
> Hi
>
> Have a question about DLinq.
>
> The example code floating around looks like this:
>
> Northwind db = new Northwind(@"C:\...\northwnd.mdf");
> var custs = from c in db.Customers where c.City == "London" select c;
>
> How does this work. Will it retreive all the rows from the Customer table
> and then filter and select. Or does it generate a sql on the fly which will
> return only the proper rows.
>
> Or am I getting it all wrong.
>
>

[microsoft.public.dotnet.languages.csharp]

[Senna]

Hi

I found a document which explains everything one need to know about DLinq.
It certainly made me drool. To bad one have to wait until 2008 or so. :)

DLinq, .NET Language Integrated Query for Relational Data at
http://download.microsoft.com/downlo...20Overview.doc

Cheers / Senna

"jeremiah johnson" wrote:

It creates SQL, but not like you're thinking. note that the FROM clause
is before the SELECT clause. Think of it as a collection of objects,
that you query, not a database. That's the point of dlinq.

watch this video: http://channel9.msdn.com/Showpost.aspx?postid=114680

dlinq is much more powerful than SQL+DataBase.

jeremiah

Senna wrote:

Ok, so
from c in db.Customers where c.City == "London" select c
does create a sql on the fly. Good to know.

Thanks for your answers.

"Richard Blewett [DevelopMentor]" wrote:

No, quite the opposite. The data already exists in the database and its using standard database functionality to extract only the data that matches the filter. The alternative would be to bring the one million rows back to the client and filter them there which would be a nightmare scenario in terms of network traffic and client processing required

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

nntp://news.microsoft.com/microsoft.public.dotnet.languages.csharp/<38**********************************@microsoft.co m>

Won't that be a performance hit for large amount of data. What if the
Customers table contains one million rows, these have to be sent over the
network and after the filtering is done it may onlybe 50 rows left that are
any use.

"Richard Blewett [DevelopMentor]" wrote:

> The filtering is performed on the server in this case
>
> Regards
>
> Richard Blewett - DevelopMentor
> http://www.dotnetconsult.co.uk/weblog
> http://www.dotnetconsult.co.uk
>
> Hi
>
> Have a question about DLinq.
>
> The example code floating around looks like this:
>
> Northwind db = new Northwind(@"C:\...\northwnd.mdf");
> var custs = from c in db.Customers where c.City == "London" select c;
>
> How does this work. Will it retreive all the rows from the Customer table
> and then filter and select. Or does it generate a sql on the fly which will
> return only the proper rows.
>
> Or am I getting it all wrong.
>
>

[microsoft.public.dotnet.languages.csharp]

[Frans Bouma [C# MVP]]

jeremiah johnson wrote:

It creates SQL, but not like you're thinking. note that the FROM
clause is before the SELECT clause. Think of it as a collection of
objects, that you query, not a database. That's the point of dlinq.

watch this video: http://channel9.msdn.com/Showpost.aspx?postid=114680

dlinq is much more powerful than SQL+DataBase.

No, that's Linq, not DLinq. Linq is very powerful. DLinq is an
implementation on top of Linq for O/R mapping purposes, and not very
well done at this point. What you refer to is the Linq system.

FB

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