mysql - SQL statement to count corresponding entries while having a strict sequence (logical) -


i want aggregate number of (identical) parts in production plan while preserving sequence.

my table looks this:

------------------------------------------------- |part number | production sequence number | .... | ------------------------------------------------- |           1|                           1| .... | -------------------------------------------------- |           1|                           2| .... | -------------------------------------------------- |           2|                           3| .... | -------------------------------------------------- |           2|                           4| .... | -------------------------------------------------- |           1|                           5| .... | --------------------------------------------------

and need count amount of same parts in row:

expected result:

------------------------------------------------- |part number | nr of pieces in row      | .... | ------------------------------------------------- |           1|                           2| .... | ------------------------------------------------- |           2|                           2| .... | ------------------------------------------------- |           1|                           1| .... | -------------------------------------------------

can done unsing sql (mysql)?

you may use variable emulate numbers , perform group by

select id, count(*) (     select          @row_number:=case             when @seq_num = id @row_number             else @row_number + 1         end num,         @seq_num:=id id,         seq_num     tab, (select @row_number:=0, @seq_num := 1) t     order seq_num ) t group num, id

demo


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