Adding up Alias with other MySQL column value - mysql

Question

I have one problem with this query; I can't seem to get ((total + rec_host) / 2) AS total2 to work. How would I go about this procedure without doing:
((((rank_ur + rank_scs + rank_tsk + rank_csb + rank_vfm + rank_orr) / 6) + rec_host ) / 2)
Here's my Query:
SELECT host_name,
SUM(rank_ur) AS cnt1,
SUM(rank_scs) AS cnt2,
SUM(rank_tsk) AS cnt3,
SUM(rank_csb) AS cnt4,
SUM(rank_vfm) AS cnt5,
SUM(rank_orr) AS cnt6,
SUM(IF(rec_host = 1,1,0)) AS rh1,
SUM(IF(rec_host = 0,1,0)) AS rh2,
((rank_ur + rank_scs + rank_tsk + rank_csb + rank_vfm + rank_orr) / 6) AS total,
((total + rec_host) / 2) AS total2
FROM lhr_reviews
GROUP BY host_name
ORDER BY total
DESC LIMIT 0,10

Answer 1

Use a subquery like so:
SELECT
host_name,
cnt1,
cnt2,
cnt3,
cnt4,
cnt5,
cnt6,
rh1,
rh2,
total,
((total + rec_host) / 2) AS total2
FROM
(
SELECT host_name,
rec_host,
SUM(rank_ur) AS cnt1,
SUM(rank_scs) AS cnt2,
SUM(rank_tsk) AS cnt3,
SUM(rank_csb) AS cnt4,
SUM(rank_vfm) AS cnt5,
SUM(rank_orr) AS cnt6,
SUM(IF(rec_host = 1,1,0)) AS rh1,
SUM(IF(rec_host = 0,1,0)) AS rh2,
((rank_ur + rank_scs + rank_tsk +
rank_csb + rank_vfm + rank_orr
) / 6) AS total
FROM lhr_reviews
GROUP BY host_name, rec_host
) t
ORDER BY total
DESC LIMIT 0,10;

Answer 2

What you could do is this:
select x.*, ((x.total + rec_host) / 2) AS total2
from (
SELECT host_name, rec_host,
SUM(rank_ur) AS cnt1,
SUM(rank_scs) AS cnt2,
SUM(rank_tsk) AS cnt3,
SUM(rank_csb) AS cnt4,
SUM(rank_vfm) AS cnt5,
SUM(rank_orr) AS cnt6,
SUM(IF(rec_host = 1,1,0)) AS rh1,
SUM(IF(rec_host = 0,1,0)) AS rh2,
((rank_ur + rank_scs + rank_tsk + rank_csb + rank_vfm + rank_orr) / 6) AS total
FROM lhr_reviews
GROUP BY host_name
ORDER BY total
DESC LIMIT 0,10
) as x
;
You cannot use the column as an alias when the alias and other column are in the same level of SELECT. So you can use a derived query which lets you basically rename your columns and/or name any computed columns.Check on Rubens Farias and Rob Van Dam answer here
PS: will search for a better article to update the answer :)