Rename a select column in sql

Question

I have a question about SQL. Here is the case: I have a table with 5 columns (C1...C5) I want to do

 select (C1+C2*3-C3*5/C4) from table;

Is there any way of naming the resulting column for referring later in a query ?

Answer 1

SELECT (C1+C2*3-C3*5/C4) AS formula FROM table;

You can give it an alias using AS [alias] after the formula. If you can use it later depends on where you want to use it. If you want to use it in the where clause, you have to wrap it in an outer select, because the where clause is evaluated before your alias.

SELECT * 
FROM (SELECT (C1+C2*3-C3*5/C4) AS formula FROM table) AS t1
WHERE formula > 100