Help with DB Query node

Hello, I am attempting to migrate one of my workflow to DB to improve efficiency.

To do so I am using a text to SQL engine to try to produce SQL code matching what I am otherwise doing using math formula node.

I have several questions:

1/ From a general standpoint, am I right to assume that if I want to produce the same result as a math formula node with a DB query node I need, in sql, to instruct to

(a) create a new column and (b) fill this newly created column with the results from a given computation?

2/ I have received numerous times the error: “database view place holder (#Table#) must not be replaced.”

Shall I conclude that all DB Query node must absolutely start with this statement?

I would appreciate if someone could explain or point to non-specialist documentation regarding this “place holder” thing.

3/ The specific text 2 SQL query I am trying to run is the following:

SELECT FROM #Table# AS `table; ALTER TABLE `table`ADD XYZ DECIMAL(10,2); UPDATE`Table`SET XYZ =`Column1` + (`Column2`

Column3

);

Can someone point out to me what are the error(s)?

Many thanks

NB