Hi Openminded,
I am not sure what your question is. But here is a transformation of the selects you gave which might be helpful to you.
Just remember that the unary plus (+) or minus (-) have a higher precedence than multiplication or division, which in turn also have a higher precedence than addition or substration.
Finally the calculation is executed from left to right (if not overridden by the precedence of operators or parentheses):
select 1 - 2
This is a simple substraction
select 1 + 1 * 2
This translates to 1 + (1 * 2)
select 1 +-+ 1 * 2
This translates to (1 + ((-(+1)) * 2))
select 1 +0+ 1 * 2
This translates to ((1 + 0) + (1 * 2))
select 1 ++ 1 * 2
This translates to (1 + ((+1) * 2))
Best Regards,
Chris Büttner