SQL Timestamp Where clause 30 mins ago

How can I see if a time stamp was from >= 30 mins ago? Sorry if I am not des开发者_如何学Pythoncriptive enough but idk what else to say.

SELECT * FROM table_name where timestamp_field < DATE_ADD(CURRENT_TIMESTAMP(), INTERVAL -30 MINUTE);

NOW()-1800<=$THE_TIME_STAMP

the above obviously is wrong, should be

unix_timestamp()-1800<=$THE_TIME_STAMP

select
   *
from
   tbl
where
   timestampdiff(minute, tbl.`date_time_field`, now()) >= 30

timestampdiff() @ mysql.com

convert(datetime, @ts) >= dateadd(minute, -30, getDate())

Replace @ts with your actual timestamp value.