[PGS9.2] Usage of GREATEST and LEAST

/********************************************************************************************
-- Title : [PGS9.2] Usage of GREATEST and LEAST
-- Reference : postgresql.org
-- Key word : greatest lest min max
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-- initiate table

drop table ttt;

-- create table

create table ttt

(a int, b varchar(100));

-- insert data

insert into ttt

select generate_series, 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'

from generate_series(1,1000, 1);

-- samples

select greatest(a, 100, null), least(a, 100, null)

from ttt;

select greatest(1,2,3,4,5,null), least(2,3,4,null, 5)

     , greatest(null, null), least(null, null)

select greatest(1, 'aaa');   -- occur error!

select greatest('aaa', 'bbb'), least('aaa', 'bbb');