CODEWITHSUNDEEP
sqlarrayspresto
Rex Salisbury
Rex Salisbury

Reputation: 478

How to use SQL to flatten a table with arrays in multiple columns?

How do I transform this table with arrays in num and letter columns:

 id  |    num    |  letter
-----+-----------+-----------
 111 | [1, 2]    | [a, b]
 111 | [3, 4]    | [c, d]
 222 | [5, 6, 7] | [e, f, g]

into this table

 id  | num | letter
-----+-----+--------
 111 |   1 | a
 111 |   2 | b
 111 |   3 | c
 111 |   4 | d
 222 |   5 | e
 222 |   6 | f
 222 |   7 | g

Appendix: here is some sql to play around with to try to perform the transformation

with test as(
  select * from (
    values
        (111, array[1,2], array['a','b']),
        (111, array[3,4], array['c','d']),
        (222, array[5,6,7], array['e','f', 'g'])
  ) as t (id, num, letter)
)
select
 *
from test

Upvotes: 1

Views: 5313

Answers (1)

Gordon Linoff
Gordon Linoff

Reputation: 1269973

PrestoDB seems to support unnest() with multiple arguments:

select t.id, u.n, u.l
from test cross join
     unnest(num, letter) as u(n, l)

Upvotes: 3

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