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/*******************************************************************************
-- Title : [PGS9.2] Example of NULLS {FIRST | LAST ]
-- Reference : postgresql.org
-- Key word : postgresql order by null first last 정렬 우선
*******************************************************************************/
-- Initiate
drop table ttt;

-- create table
create table ttt 
( aa serial not null
, bb varchar(10) null
);

-- load data
insert into ttt(bb)
values ('ggg')
     , (null)
     , ('uuu')
     , ('ddd')
     , ('eee')
     , ('kkk')
     , ('aaa')
     , (null)
     , ('yyy');

-- query table
select * from ttt;

-- using "order by" using nulls first and last
select * from ttt order by bb asc;  /*opposite sql server, same with 'nulls last'*/
select * from ttt order by bb asc nulls first;
select * from ttt order by bb asc nulls last;

select * from ttt order by bb desc;
select * from ttt order by bb desc nulls first;
select * from ttt order by bb desc nulls last; 

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