Names That Don't Match Their Email

The CRM team suspects duplicate accounts. Every email in customers follows one house pattern: the customer's name in lower case, the space turned into a dot, then @email.com — John Smith is john.smith@email.com. An account whose name does not produce its own email is a data-quality flag, and usually a second account for someone who already has one.

Show exactly these 5 columns, in this order: customer_id, name, email, name_handle (the name in lower case with every space replaced by a dot), and original_id (the customer_id of the *other* account with the same email whose name *does* produce it — NULL if there is none). Return only the accounts whose name_handle differs from the part of their email before the @. Order by customer_id.

Two string moves do the work: build a handle from the name, cut the local part out of the email, compare the two. Then the table joins to itself on email to find the account the address really belongs to — and that join needs the same handle test, applied to the *other* row.

Mind the punctuation: Emma W. keeps its full stop, so her handle is emma.w. — nothing to strip, and it still does not match.