PL/SQL mini tricks

base64toDB.sql

select UTL_ENCODE.BASE64_DECODE(utl_raw.cast_to_raw('<base64_string>')) from dual;

concatenated-results.sql

select
(select rtrim(xmlagg(xmlelement(el, nvl(t.column1, t.column2 || ' ' || t.column3) || ','))
    .extract('//text()'),
    ',')
from table_name t

duration_between_dates.sql

select (dateLast-dateFirst) * decode( upper('SS'/* one of the operands */), 'SS', 24*60*60, 'MI', 24*60, 'HH', 24, NULL ) from dual;

split_string_example.sql

select * from
(select 5 c from dual
  UNION
 select 6 c from dual)
 where c in (
     select regexp_substr('2,5,3','[^,]+', 1, level) from dual
     connect by regexp_substr('2,5,3', '[^,]+', 1, level) is not null
);