1.int装string

select CAST (1234 AS text)

select to_char(1234，’999‘)

2.string转int
 select cast('999' as NUMERIC)

--5 附: PostgreSQL 类型转换函数

Function	Return Type	Description	Example
to_char (timestamp, text )	text	convert time stamp to string	to_char(current_timestamp, 'HH12:MI:SS')
to_char ( interval, text )	text	convert interval to string	to_char(interval '15h 2m 12s', 'HH24:MI:SS')
to_char ( int, text )	text	convert integer to string	to_char(125, '999')
to_char ( double precision , text )	text	convert real/double precision to string	to_char(125.8::real, '999D9')
to_char ( numeric, text )	text	convert numeric to string	to_char(-125.8, '999D99S')
to_date (text, text )	date	convert string to date	to_date('05 Dec 2000', 'DD Mon YYYY')
to_number ( text, text )	numeric	convert string to numeric	to_number('12,454.8-', '99G999D9S')
to_timestamp ( text, text )	timestamp with time zone	convert string to time stamp	to_timestamp('05 Dec 2000', 'DD Mon YYYY')
to_timestamp ( double precision )	timestamp with time zone	convert Unix epoch to time stamp	to_timestamp(1284352323)