re use existing selected column in sql server?

Question

Say I have a query that goes like this

select column1
,column2
,column3
,column4
,column5 + reusethiscolumn as Reusethiscolumn2

[can i use here the data that will be derived from the column below?]

,case[computation here] as reusethiscolumn
from table

is there any way to do this? thanks in advance.

It is possible , to provide solution give some data and result — Azar, Jun 27 '14 at 08:04
Possible duplicate of http://stackoverflow.com/questions/6591183/t-sql-column-alias-on-computed-column-invalid-column-name — VMai, Jun 27 '14 at 08:13
No, you can't use a column alias at this point without using a subselect. You can use a column alias in the `ORDER BY` clause, see column_alias can be used in an ORDER BY clause. MySQL extends the use of column alias names to the `HAVING` and `GROUP BY` clauses — VMai, Jun 27 '14 at 08:16
SQL processes all columns in the `SELECT` clause "as if" they're all being evaluated in parallel - this means that within a single `SELECT` clause, you can't have one column's computation rely upon a different column's value — Damien_The_Unbeliever, Jun 27 '14 at 08:32

score 1 · Accepted Answer · answered Jun 27 '14 at 08:50

1

select 
column1
,column2
,column3
,column4
,(column5 + reusethiscolumn) as Reusethiscolumn2
from
(
  select 
    column1
   ,column2
   ,column3
   ,column4
   ,column5
   ,case[computation here] as reusethiscolumn
  from table
) AS SubQ

answered Jun 27 '14 at 08:50

Vigi Tri

156
10

re use existing selected column in sql server?

1 Answers1