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#include <iostream>
#include <random>

int randomInRange(int min, int max, std::mt19937 &eng) {
  std::uniform_int_distribution<> distr(min, max); // define the range
  return distr(eng);
}

int main() {
  std::random_device rd; // obtain a random number from hardware

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sudo mount -o remount,rw /your/device/here

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# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             postgres                                peer

local   all             all                                     md5
# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5

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rpad(string text, length int [, fill text]) 
fill is space by default

select rpad('hello', 10, 'w') -- hellowwwww
select lpad('hello', 10, 'p') -- ppppphello
select lpad('hello', 10)      -- '     hello'
select rpad('hello', 4)       -- hell

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select date_part('month', '2011-10-22'); -- 10
select extract(month from '2011-12-22'); -- 12

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select count(case when some_col>10 then 1 end) as some_alias;
select count(*) filter(where some_col>10) as some_alias;
-- same can be applied to any aggregation function

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select coalesce(col1, col2); -- return first col, which is not null
select nullif(val1, val2);   -- return null if val1==val2, otherwise return val1

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select generate_series('2016-12-31'::date, '2017-02-03'::date, '2 days'); -- series of days with interval of 2 days
select generate_series(1, 5, 2); -- 1, 3, 5

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select date_trunc('month', '2011-12-12'); -- '2011-12-01 00:00:00.000000'

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select generate_subscripts(array[array[1,2,3], array[4,5,6]], 2); -- 1,2,3
select generate_subscripts(array[array[1,2,3], array[4,5,6]], 1); -- 1,2