Select 2 columns in one and combine them

(SELECT column1 as column FROM table )
UNION 
(SELECT column2 as column FROM table )

Yes, just like you did:

select something + somethingElse as onlyOneColumn from someTable

If you queried the database, you would have gotten the right answer.

What happens is you ask for an expression. A very simple expression is just a column name, a more complicated expression can have formulas etc in it.

Yes,

SELECT CONCAT(field1, field2) AS WHOLENAME FROM TABLE
WHERE ...

will result in data set like:

WHOLENAME
field1field2