OK, if a SELECT statement is sufficient by itself, surely you can tell me the results of this:

    SELECT * FROM stuff WHERE thing=2

Of course you can't. Because every declarative process has two main steps: declare and execute. SELECT and enter() both only declare; they must then be executed against data in an engine to produce a result.

What we mean when we say "SQL is declarative" is that it doesn't provide instructions on how to carry out a task, and instead only provides a description of the outcome of the task, once it's been carried out. SELECT is declarative because it doesn't tell the computer how to do a query. SELECT tells the interpreter what you want not how to get it.