Tech Tock

Time is of the essence.

VS 2010 – 5 – 10 Years

Visual Studio 2010 can compare SQL Server Databases.  Of course my software from 2000, and RedGate from slightly later could do that too.  Mine could also compare data…

While I still love my platform and think VS 2010 is awesome, if you’re looking for utilities, what you’ll see in 2015 is probably already out there today.

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October 6, 2010 Posted by | Uncategorized | , , | 1 Comment

LINQ Group By With Multiple Aggregates

It appears that LINQ does not support a query that outputs multiple group by aggregate fields.  For example, there’s Min() and a Max() functions, so to get both min & max from a list, you seem to need to make 2 LINQ queries:

 var min = (from d in data select d).Min();
 var max = (from d in data select d).Max();

In SQL, the 2 values would pop out easily from a single query:

 Select min(d), max(d) from data

LINQ has all the power of SQL and works similarly, just the syntax is different.  To achieve this result we have to use a group by.  But we’ll be grouping by nothing, including all items in the set in a single bucket. I usually group by “1”, which makes a single grouping of all the elements (grouping by any single object will do the same):

 var minMax = from d in values
    group d by 1 into g
    select new { Min = g.Min(x => x),
     Max = g.Max(x => x) };

 

minMax.First() now contains the min and max for the set of values.

November 18, 2009 Posted by | Uncategorized | , , , , , , , , , | 7 Comments