@Mogima &
@Lyanhyrt: The line of code is from a database-oriented language called MySQL. It's a query to database and translates into "delete all entries from the customers database table". This is a MAJOR no-no dealing with databases, second only to the DROP instruction (a.k.a. destroy a table and everything on it).
However, a thing: you cannot simply
walk into Mordor use a query, it has to be written and coded beforehand. So what he's seeing is probably not his code, it's somebody else's. Probably is that query what he thinks that doesn't belong there. (Using queries like that isn't unusual in testing phases) That again, maybe he's cheching the DB so maybe he's in a world of trouble.