Sql of note

Example of Time bucket

select
 from_unixtime(timestamp-timestamp%3600)as time,
 count(*)
from
 table
where
 data like 'Destination directory %does not exist at%' and
 FROM_UNIXTIME(timestamp) > subdate(now(),interval 4 day)
group by timestamp-timestamp%3600
order by time;

sqlite

.tables

.schema

Date / Time

These all return dates and times.

Last day of this month:

SELECT date('now','start of month','+1 month','-1 day');

the first day of this monnth:

SELECT date('now','start of month');

first day of last month:

SELECT date('now','start of month','-1 month');

last day of last month:

SELECT date('now','start of month','-1 day');

get epoch:

select strftime( '%s' , "2012-09-30") ;

convert from epoch to date:

SELECT datetime( 1092941466 , 'unixepoch');

convert back and forth:

SELECT datetime( strftime( '%s' , "2012-09-30") , 'unixepoch');

X in Y

SELECT filename FROM source WHERE hash NOT IN (SELECT hash FROM destination);

Also see

• Eve SQL of note
• EXPLAIN and Example of JOIN
• Properties Table

transpose wide tables

https://www.periscopedata.com/blog/using-row-numbering-and-full-joins-to-transpose-wide-tables

grouping

Redshift:

https://docs.aws.amazon.com/redshift/latest/dg/r_Examples_of_avg_WF.html

multiple agregates

https://blog.jooq.org/2017/04/20/how-to-calculate-multiple-aggregate-functions-in-a-single-query/

generate a sequence

select a.a as a, b.a as b , c.a as c ,
CAST(a.a AS INTEGER ) as aint,
CAST(b.a AS INTEGER ) as bint,
CAST(c.a AS INTEGER ) AS cint,
CAST(a.a AS INTEGER ) * 100 + CAST(b.a AS INTEGER ) * 10 + CAST(c.a AS INTEGER ) AS sum 
from       (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as a
cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as b
cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as c ;

wow that's coplicated, we are postgres s lets try something simpler:

SELECT a.n
from generate_series(1, 100) as a(n), generate_series(1, 3)

reference: https://stackoverflow.com/questions/23358333/how-can-i-generate-a-series-of-repeating-numbers-in-postgresql