Postgresql - Function that generates random phone number - sql

Question

I'm very new to postgresql and I'm wondering how to go about creating a function that will generate random phone numbers in [phone] format. I can't even wrap my head around how to do this so if anyone has any feedback that would be great.

Answer 1

To generate a single, completely random number in the requested format:
SELECT format('(%s%s%s) %s%s%s-%s%s%s%s'
, a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10])
FROM (
SELECT ARRAY (
SELECT trunc(random() * 10)::int
FROM generate_series(1, 10)
) AS a
) sub;
Returns:
[phone]
Or similar.

Answer 2

Not the most elegant of code but it's very simple so should give you a basis to work from:
SELECT '('
|| (RANDOM() * 9)::INT
|| (RANDOM() * 9)::INT
|| (RANDOM() * 9)::INT
|| ') '
|| (RANDOM() * 9)::INT
|| (RANDOM() * 9)::INT
|| (RANDOM() * 9)::INT
|| '-'
|| (RANDOM() * 9)::INT
|| (RANDOM() * 9)::INT
|| (RANDOM() * 9)::INT
|| (RANDOM() * 9)::INT;

Answer 3

I was thinking of this:
select replace(replace(replace('(#n1) #n2-#n3),
'#n1', lpad((random()*1000)::int::text, 3, '0')
), '#n2', lpad((random()*1000)::int::text, 3, '0')
), lpad((random()*10000)::int::text, 4, '0')
)
That is, use three different random numbers, one for each grouping.
The arithmetic would be slightly different if you don't allow one or more elements to start with a zero.

Answer 4

select regexp_replace(CAST (random() AS text),'^0\.(\d{3})(\d{3})(\d{4}).*$','(\1)\2-\3') AS random;
The random() function is used to generate a random number between 0 and 1. It is then CAST as text and a regexp_replace is used to add the formatting characters.
Updated to pad the string with some arbitrary numbers:
select regexp_replace(rpad(CAST (random() AS text),12,CAST(random() AS text)),'^0\.(\d{3})(\d{3})(\d{4}).*$','(\1)\2-\3') AS random;
There is no guarantee this will produce valid phone numbers - for example area codes can't start with zero or one, but if you just need to fill in some numbers quickly, this should do the trick.