Searching Discount Codes

Shopify Partner
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I have been searching through the forum and support to see if there is an easy way to search discount codes. Basically I need to track orders for a fundraising program, I need to know which orders belong to which group. I thought about creating unique discount codes for each group with free shipping. But, there doesn't seem to be an easy way to search discount codes.

I did find this support page where it says to sort by discount code. But, the only way I can figure out how to do this is to export a CVS file, then sort in Excel. It'll work for what I need, but thought there must be an easier way.

Any suggestions? I don't want to go with an affiliate app since they take a % of sales.