postgresql - sql - aggregate count and share by group -

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with table t1 below, need count each make , share each make

+--------+ | make   | +--------+ | toyota | | audi   | | bmw    | | bmw    | | audi   | +--------+

with below can get car_cnt per make 

select  make  , count (*) car_cnt t1 group make

how share (%) each make ?

using count analytic function, can make single pass on table , compute market share each car.

select distinct     make,     count(*) on (partition make) car_cnt,     100.0 * count(*) on (partition make) / count(*) on () car_pct t1

output:

    make    car_cnt car_pct 1   audi    2       40 2   bmw     2       40 3   toyota  1       20

demo here:

rextester


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