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are you looking for DLP across both email and Drive?
Having worked with a number of products that provide Drive DLP for Google Apps and seen some pre-defined regexes, they can be quite complex depending on the type of data you are trying to detect.
Google provide some typical simple examples at https://support.google.com/a/answer/1371417?hl=en
I have found http://www.regular-expressions.info/index.html useful
Do you need to meet specific compliance requirements such as PCI? What type of data are you trying to detect?