How to extract all values except the last value in a string separated by comma in sql

[Muhammad Akhtar]

I am think of SUBSTRING_INDEX but dont know how to extract all values except the last value in a string separated by comma

e.g :
value is "aaa,bbb,ccc,ddd"
desired result is "aaa,bbb,ccc"

e.g :
value is "a1,b2,c3,d4,e5"
desired result is "a1,b2,c3,d4"