Athena- extract substring from string - comma delimited - amazon-web-services

Question

I want to create Athena view from Athena table.
In table, the column value is "lastname, firstname" so I want to extract these values as 'lastname' and 'firstname' and then need to store it into seperate columns in a view. example- firstname need to be stored into new column- 'first_name' and lastname need to be store into new column - 'last_name'
whats the SQL function which I can use here? I tried split function but then it's giving me an array.

Answer 1

Assuming the input strings have a fixed and known number of elements, you can do something like this:
WITH data(value) AS (
VALUES ('Aaa,Bbb')
)
SELECT elements[1], elements[2]
FROM (
SELECT split(value, ',') AS elements
FROM data
)
=>
_col0 | _col1
-------+-------
Aaa | Bbb
(1 row)

Answer 2

create or replace view "names" as
select
SPLIT_PART("column_name",',', 1) as first_name
, SPLIT_PART("column_name", ',', 2) as last_name
from myTable

Answer 3

You can use UNNEST on the split result:
WITH dataset AS (
SELECT * FROM (VALUES
('aaa,bbb'),
('aaa1,bbb1')
) AS t (str))
SELECT str_col
FROM dataset
CROSS JOIN UNNEST(split(str, ',')) as tmp(str_col)
Output:
str_col
aaa
bbb
aaa1
bbb1
UPD
If you have at least one comma guaranteed than it is as easy as:
WITH dataset AS (
SELECT * FROM (VALUES
('aaa,bbb'),
('aaa1,bbb1')
) AS t (str))
SELECT splt[1] last_name, splt[2] first_name
FROM
(SELECT split(str, ',') as splt
FROM dataset)
Output:
last_name
first_name
aaa
bbb
aaa1
bbb1
In case you can have varing number of commas but limitied to some number you can use TRY:
WITH dataset AS (
SELECT * FROM (VALUES
('aaa,bbb'),
('aaa1,bbb1,ddd1')
) AS t (str))
SELECT splt[1], splt[2], TRY(splt[3])
FROM
(SELECT split(str, ',') as splt
FROM dataset)
Output:
_col0
_col1
_col2
aaa
bbb
aaa1
bbb1
ddd1