http://www.postgresqltutorial.com/postgresql-string-functions/
// SELECT
select p_id,p_name from p_tb;
select p_id,p_name from p_tb;
where p_name like '%foo%';
// ADD column
alter table p_tb
add column p_id integer,
add column p_name character varying(250),
add column p_pk serial primary key;
// DELTE column
alter table p_tb
drop column p_name;
// RENAME column
alter table p_tb
rename column p_name to p_name_t;
// UPDATE column
update p_tb
set name_ul = name;
update p_tb
set name_ul = initcap(name) where language = 'vietnam';
:: String Functions ::
ASCII(‘A’) >>> 65CHR(65)
CONCAT(‘A’,’B’,’C’)
CONCAT_WS CONCAT(‘,’,’A’,’B’,’C’)
FORMAT(‘Hello %s’,’PostgreSQL’)
INITCAP(‘hI tHERE’) >>> Hi There
LEFT(‘ABC’,1)
LENGTH(‘ABC’)
LOWER(‘hI tHERE’)
LPAD(‘123′, 5, ’00’)
LTRIM(‘00123’)
MD5(‘ABC’)
POSTION(‘B’ in ‘A B C’)
REGEXP_MATCHES SELECT REGEXP_MATCHES(‘ABC’, ‘^(A)(..)$’, ‘g’);
REGEXP_REPLACE(‘John Doe’,'(.*) (.*)’,’\2, \1′);
REPEAT(‘*’, 5)
REPLACE(‘ABC’,’B’,’A’) >>> ‘AAC’
REVERSE(‘ABC’)
RIGHT(‘ABC’, 2)
RPAD(‘ABC’, 6, ‘xo’)
RTRIM(‘abcxxzx’, ‘xyz’)
SPLIT_PART(‘2017-12-31′,’-‘,2)
SUBSTRING(‘ABC’,1,1)
TRIM
UPPER(‘hI tHERE’)
