Using variable in sql select

stanimir_p · #1 (**permalink**) 02-08-07, 15:38

Hi
Can I use select query that way:

select a, b ,b*100/a as c, c-a/b, from mytable;
how to use result "c" in the same query?

in Microsoft Access it is possible but how to do with mysql -3.23 version
if it is possible only in new version of mysql please let I know.
Thanks

r937 · #2 (**permalink**) 02-08-07, 16:31

you can do this two ways

one, just use the expression instead of the alias

Code:

select a, b ,b*100/a as c, b*100/a-a/b, from mytable

two, upgrade to 4.1 to be able to use a subquery

stanimir_p · #3 (**permalink**) 02-09-07, 03:10

ofcource I can.
select a, b ,b*100/a as c, b*100/a-a/b, from mytable
that will work
you know, the idea is when I want to use
b*100/a many times as variable "c"
and MySql should not to multiplay and divide every time

select a, b ,b*100/a as c, c-a/b, c+d/a as e, e*100/b from mytable

what is the way to use these variables "c" and "e" in mysql 4.1 or 5.0

r937 · #4 (**permalink**) 02-09-07, 04:43

Quote:

Originally Posted by stanimir_p

what is the way to use these variables "c" and "e" in mysql 4.1 or 5.0

Code:

select a, b, c, c-a/b, e, e*100/b 
  from (
       select a, b, b*100/a as c, b*100/a+d/a as e
         from mytable
       ) as dt

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