How can i execute this query faster? - mysql

Question

This is my query:
create table vi_all as
select
d.primaryid, d.age, d.gndr_cod, d.wt, d.wt_cod, d.reporter_country,
dr.primaryiddrug, dr.role_cod, dr.drug_name,
r.primaryidreac, r.pt,
o.primaryidoutc, o.outc_cod,
i.primaryidindi, i.indi_pt
FROM demo d,
drug dr,
reac r,
outc o,
indi i;
Each table contains at least 80K records and more than 20 fields so its getting really tough to execute select statement on multiple tables; and i just want 4 or 3 fields from each table so i thought of this, but the above query has taken more than 5 hours but still has not given back any result.

Answer 1

My crystal ball says you need something like this:
create table vi_all as
select
d.primaryid, d.age, d.gndr_cod, d.wt, d.wt_cod, d.reporter_country,
dr.primaryiddrug, dr.role_cod, dr.drug_name,
r.primaryidreac, r.pt,
o.primaryidoutc, o.outc_cod,
i.primaryidindi, i.indi_pt
FROM demo d
LEFT JOIN drug dr ON d.drug=dr.id
LEFT JOIN reac r ON d.reac=r.id
LEFT JOIN outc o ON d.outc=o.id
LEFT JOIN indi i ON d.indi=i.id;
As far as I can tell your query is selecting all results from all tables but not assocating them in anyways so, you can maybe get duplicate data in the newly created table. Also, if you have some good foreign keys to associate those tables, the performance will be considerably better.