需要在仅返回一行的外连接中创建表达式

I'm creating a really complex dynamic sql, it's got to return one row per user, but now I have to join against a one to many table. I do an outer join to make sure I get at least one row back (and can check for null to see if there's data in that table) but I have to make sure I only get one row back from this outer join part if there's multiple rows in this second table for this user. So far I've come up with this: (sybase)I'm creating a really complex dynamic sql, it's