c# - Linq Query Datatable and Group by multiple columns -


suppose have following datatable loaded in memory db query:

col_a:     col_b:     col_c:    col_d:    date1:     date2: a1         b1         c1        d1        dt1_1      dt2_1 a1         b2         c2        d2        dt1_1      dt2_2 a1         b3         c3        d3        dt1_1      dt2_3 a1         b4         c4        d4        dt1_2      dt2_4 a1         b5         c5        d5        dt1_2      dt2_5

and, in terms of dates, assume, example, "_1" < "_2". so, want is, each value in col_a, 1 row each date1 earliest date2.

so, given data, i'd want back:

col_a:     col_b:     col_c:    col_d:    date1:     date2: a1         b1         c1        d1        dt1_1      dt2_1 a1         b4         c4        d4        dt1_2      dt2_4

in other words, since date1 changed, data earliest date2. hope makes sense.

in sql i'd kind of imagine query looking follows:

select col_a, col_b, col_c, col_d, date1, date2,        rank() over(partition col_a, date1 order date2) rn mytable rn = 1 order col_a, date1, date2

but how create in linq , new datatable (filtered) results?

check out link linq rank() , case when in vb.net , sub link shows date aggregate: linq sql vb.net assistance


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