remove duplicate from fields

I have table like this
id|type
1|math,science
2|math,science,math
3|science,science
4|math
5|science
6|programming,math,math
7|programming

i want to remove duplicated to will be like this
id|type
1|math,science
2|math,science
3|science
4|math
5|science
6|programming,math
7|programming
i tried to use array_unique but i can't update table???!

See original post by mero2020