I have a table with some example columns below:
id creationdate name
1 2012-08-09 14:14:22.225 ken
2 2012-08-09 13:11:20.212 john
I want to get all rows where creationdate is older than 30 min. from now.
You want to make sure the creation date value is LESS than now minus 30, not greater. The lower the value of a datetime, the older it is.