jdunstan·5 ปีที่แล้ว·discussw3schools and the online documentation for any database are good places to start (Postgres and SQL Server have pretty good documentation).There are also easy-to-google SQL Puzzles, if you're looking for something more advanced.I would also recommend learning about query plans and how to read them, they're invaluable for query optimization.
jdunstan·5 ปีที่แล้ว·discussThat's very close to SELECT *, which has it's own dangers. I agree that it would be nice for exploration and testing, but probably should not be used in production.
There are also easy-to-google SQL Puzzles, if you're looking for something more advanced.
I would also recommend learning about query plans and how to read them, they're invaluable for query optimization.