How to unpack Array to Rows in Snowflake? - sql

Question

I have a table that looks like the following in Snowflake:
ID | CODES
2 | [ { "list": [ { "item": "CODE1" }, { "item": "CODE2" } ] } ]
And I want to make it into:
ID | CODES
2 | 'CODE1'
2 | 'CODE2'
So far I've tried
SELECT ID,CODES[0]:list
FROM MY_TABLE
But that only gets me as far as:
ID | CODES
2 | [ { "item": "CODE1" }, { "item": "CODE2" } ]
How can I break out every 'item' element from every index of this list into its own row with each CODE as a string?
Update: Here is the answer I got working at the same time as the answer below, looks like we both used FLATTEN:
SELECT ID,f.value:item
FROM MY_TABLE,
lateral flatten(input => MY_TABLE.CODES[0]:list) f

Answer 1

So as you note you have hard coded your access into the codes, via codes[0] which gives you the first item from that array, if you use FLATTEN you can access all of the objects of the first array.
WITH my_table(id,codes) AS (
SELECT 2, parse_json('[ { "list": [ { "item": "CODE1" }, { "item": "CODE2" } ] } ]')
)
SELECT ID, c.*
FROM my_table,
table(flatten(codes)) c;
gives:
2 1 [0] 0 { "list": [ { "item": "CODE1" }, { "item": "CODE2" }]} [ { "list": [{"item": "CODE1"}, { "item": "CODE2" }]}]
so now you want to loop across the items in list, so we use another FLATTEN on that:
WITH my_table(id,codes) AS (
SELECT 2, parse_json('[ { "list": [ { "item": "CODE1" }, { "item": "CODE2" } ] } ]')
)
SELECT ID, c.value, l.value
FROM my_table,
table(flatten(codes)) c,
table(flatten(c.value:list)) l;
gives:
2 {"list":[{"item": "CODE1"},{"item":"CODE2"}]} {"item":"CODE1"}
2 {"list":[{"item": "CODE1"},{"item":"CODE2"}]} {"item":"CODE2"}
so you can pull apart that l.value how you need to access the parts you need.