sql - How to optimize this query for my school project -


it's assignment kindly me optimize below 2 queries.

optimize assignment 1:

select      n.node_id,     min(least(n.date,ec.date)) date      n, ec      (n.node_id = ec.node_id_from or n.node_id = ec.node_id_to)     , n.date - ec.date > 0 group      n.node_id;

optimize assignment 2:

select      to_char(convert_timezone ('utc','america/los_angeles', tablea."date"), 'yyyy-mm') "date_month",     count(distinct case when (tableb."date" not null) tableb._id else null end) "tableb.countb",     count(distinct case when (tablec."date" not null) tablec._id else null end) "tablec.countc"      tablea tablea left join      tableb tableb on (date (convert_timezone ('utc', 'america/los_angeles',tableb."date"))) = (date (convert_timezone ('utc', 'america/los_angeles',tablea."date"))) left join      tablec tablec on (date (convert_timezone ('utc', 'america/los_angeles',tablec."date"))) = (date (convert_timezone ('utc', 'america/los_angeles',tablea."date")))      tablea."date" >= convert_timezone ('america/los_angeles', 'utc', dateadd (month, -17, date_trunc('month', date_trunc('day', convert_timezone ('utc', 'america/los_angeles',getdate ())))) group      1 order      1 desc  limit 500;

use short alias makes sql query shorter , cleaner. here optimized version of second query

select datepart(month, a.date-8/24) date_month,    sum(case when b.date not null 1 else 0 end) countb,   sum(case when c.date not null 1 else 0 end) countc, tablea       left join tableb b       on b.date = a.date -- timezone offsets not necessary,    left join tablec c        on c.date = a.date -- both in same timezone  a.date >= dateadd(hour, 8,             dateadd (month,-17,date_trunc('month',               getdate () )) group 1 order 1 desc limit 500;

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