How can I count distinct only the values in VARCHAR array?

Question

I have a VARCHAR column with arrays in it (string as a array) in Oracle sql dialect how can I count the distinct values in it?

for example I have the following rows

ID List 
1  ["351","364"]
2  ["364","351"]
3  ["364","951"]
4  ["951"]

I expected to count 3.

Answer 1

Assuming you're on a recent version of Oracle, you can use JSON functions to extract the elements of the arrays:

select t.id, j.value
from your_table t
outer apply json_table (t.list, '$[*]' columns (value path '$')) j

ID	VALUE
1	351
1	364
2	364
2	351
3	364
3	951
4	951

And then just count the distinct values:

select count(distinct j.value) as c
from your_table t
outer apply json_table (t.list, '$[*]' columns (value path '$')) j

C
3