postgresql - SQL update with cursors/loops -

i have 3 sql tables follows:

• table #1 has column recipeid
• table #2 has column
• table #3 has columns recipeid, alimentid, quantity

in recipes, want replace occurrences of aliment aliment b.

example:

recipeid  |  alimentid  |  quantity  ----------------------------------- recipe  | aliment   |  10. recipe  | aliment b   |   5. recipe b  | aliment c   |   2. recipe b  | aliment b   |   5. recipe c  | aliment   |   9. 

replacing aliment aliment b.

expected output:

recipeid  |  alimentid  |  quantity ----------------------------------- recipe  | aliment b   |  15. recipe b  | aliment c   |   2. recipe b  | aliment b   |   5. recipe c  | aliment b   |   9. 

another accepted output keep records quantity equal 0.

how in sql without cursor/loops ? there way update-set-select-join ? here, afraid need more set...

(i using postgresql.)

if understand correctly need

select recipeid,replace(alimentid,'aliment a','aliment b') alimentid, sum(quantity) quantity  #table3 group recipeid,replace(alimentid,'aliment a','aliment b') alimentid