SQL Server and Oracle diff from are not followed by a table but a result set

1 Select *  from 2 (3Select1+1-- in Oracle, the line is written as Select Plus num From dual4 ) t

The example here is very simple, mainly to explain the syntax differences

In line 4th, what's the matter? I'm surprised. Line 4th there is nothing at all, how can there be a hole????? MMM ~ ~ ~ ~ ~ ~ ~ This pit depressed me for half an hour.

Because I have been using Oracle for a long time, and gradually I have developed a habit that I didn't realize--not to alias the temporary result set

Yes, in line 4th if there is no alias, a syntax error is reported in SQL Server, which can be performed in Oracle

SQL Server and Oracle diff from are not followed by a table but a result set