SqlFunctions.Checksum how to get checksum for queryable

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I'm trying to figure out how to get this sql equivelant:

SQL

select checksum_agg(checksum(*)) from Foo

From linq SqlFunctions. I'm able to easily get the checksum for one column, so long as I know the column. However, I won't know column names. So I can do something like:

C#

SqlFunctions.ChecksumAggregate(Foo.Select(x => x.Id))

But that is only the checksum of one column, and I have to know the column name. Is there a way to checksum the collection like the SQL statement? Or to get the checksum a column at a time without knowing the column name?

Posted 30-Jul-13 3:28am

loctrice

Updated 30-Jul-13 4:26am

v2

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Sampath Lokuge · Answer 1 · 2013-07-30T04:14:00

Solution 1

You can use ChecksumAggregate method for this.

It's like this :

C#

using (AdventureWorksEntities AWEntities = new AdventureWorksEntities())
{
    // SqlFunctions.ChecksumAggregate is executed in the database.
    decimal? checkSum = SqlFunctions.ChecksumAggregate(
        from o in AWEntities.SalesOrderHeaders
        select o.SalesOrderID);

    Console.WriteLine(checkSum);
}

For more info check this :

http://msdn.microsoft.com/en-us/library/vstudio/dd456858(v=vs.100).aspx[^]

http://msdn.microsoft.com/en-us/library/vstudio/dd487151(v=vs.100).aspx[^]

I hope this will help to you.

Posted 30-Jul-13 4:14am

Sampath Lokuge

Updated 30-Jul-13 4:18am

v2

Comments

loctrice 30-Jul-13 10:27am

I have figured that much out. The problem I am running into is how to do that over the whole linq collection. Or, if doing it one column at a time, to be able to do it without knowing the column name and type for the checksum.

Sampath Lokuge 30-Jul-13 10:30am

What happened when you do like this :decimal? checkSum = SqlFunctions.ChecksumAggregate(
from o in AWEntities.SalesOrderHeaders
select o.*); In other words * instead of column name.

loctrice 30-Jul-13 10:48am

Linqpad gives me an invalid expression error. I don't think you can use .* in c#

Sampath Lokuge 30-Jul-13 10:52am

I am sorry.Just try like this : decimal? checkSum = SqlFunctions.ChecksumAggregate(
from o in AWEntities.SalesOrderHeaders
select o);

loctrice 30-Jul-13 10:59am

ChecksumAggregate takes IEnumerable of int so that one won't work