Question

When creating a record “grid” with custom paging what is the best/optimal way to query the total number of records as well as the records start-end using C#?

SQL to return paged record set:

SELECT Some, Columns, Here FROM (
    SELECT ROW_NUMBER() OVER (ORDER BY Column ASC) AS RowId, *
    FROM
        Records
    WHERE
        (...)
) AS tbl
WHERE ((RowId > @Offset) AND (RowId <= (@Offset + @PageSize)) )

SQL to count total number of records:

SELECT COUNT(*) FROM Records WHERE (...)

Right now, I make two trips to the server: one for getting the records, and the other for counting the total number of records.

What is/are the best way(s) to combine these queries to avoid multiple DB trips?

Answer 1

You can use stored procedure with output parameter (or return value) to pass total number of rows.

create procedure dbo.Stuff_GetAll (
    @StartRowIndex int, -- zero based
    @MaximumRows int
)
as
begin
    declare @TotalRows int

    select @TotalRows = count(*) 
    ...

    if (@TotalRows > 0 and @MaximumRows > 0)
    begin
        ;with T as (
            select *, row_number() over ()
            ...
        )
        select T.* from T
        where Row between @StartRowIndex + 1 and (@StartRowIndex + @MaximumRows)
    end

    return @TotalRows
end
GO

You may want to add a check to query count() only when a first page is requested (can be quite expensive).