Anybody know how to write a LINQ to SQL statement to return every nth row from a table? I'm needing to get the title of the item at the top of each page in a paged data grid back for fast user scanning. So if i wanted the first record, then every 3rd one after that, from the following names:
Amy, Eric, Jason, Joe, John, Josh, Maribel, Paul, Steve, Tom
I'd get Amy, Joe, Maribel, and Tom.
I suspect this can be done... LINQ to SQL statements already invoke the ROW_NUMBER() SQL function in conjunction with sorting and paging. I just don't know how to get back every nth item. The SQL Statement would be something like WHERE ROW_NUMBER MOD 3 = 0
, but I don't know the LINQ statement to use to get the right SQL.
Sometimes, TSQL is the way to go. I would use ExecuteQuery<T>
here:
var data = db.ExecuteQuery<SomeObjectType>(@"
SELECT * FROM
(SELECT *, ROW_NUMBER() OVER (ORDER BY id) AS [__row]
FROM [YourTable]) x WHERE (x.__row % 25) = 1");
You could also swap out the n
:
var data = db.ExecuteQuery<SomeObjectType>(@"
DECLARE @n int = 2
SELECT * FROM
(SELECT *, ROW_NUMBER() OVER (ORDER BY id) AS [__row]
FROM [YourTable]) x WHERE (x.__row % @n) = 1", n);
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