delete data from database where date ... SQL

I want to delete some data fr开发者_开发知识库om database:

WHERE created_at < NOW() - 30 min

How to wirte the 30 min into sql

Calculate older date and compare with it:

WHERE created_at < NOW() - INTERVAL 30 MINUTE

See DATE_ADD description for list of all available units.

WHERE created_at < NOW() - INTERVAL 30 MINUTE;