I didn't quite understand the first query the data from the query syntax is what, haven't seen this before, then why do you want to have such a subquery? The select data can not directly based on the truth? What special syntax or is it?
The second is the query I didn't understand the select (the select list) what is the role? Still say it is a question of books, the syntax is actually wrong? Request, solve my question, thanks!
CodePudding user response:
May not be able to oracle syntax, is other databases