[postgresql]postgresqlg use generate_ Series() function completes statistics

Catalog

1. demand

2.generate_series function

3. example

3.1 interval 1 God

3.2  interval 1 Hours

3.3 interval 1 minute

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1. demand

For example, the passing details of a gantry of the expressway are as follows ：

  demand ：
        It is necessary to count the total number of vehicles passing through the gantry by day , When there is no passing car, it is counted as 0, namely 7 month 13 If there is no record of the day, it should also be expressed as 0

with t1 as 
(
select generate_series('2022-07-10'::date,'2022-07-17'::date,'1 day') as day
),
t2 (
select 
    pass_id,
    capture_time,
    to_char(capture_time,'yyyy-mm-dd')::date as capture_date,
    grantry_code,
 from sdi_op_toll_station_pass_detail_t 
)
select day,grantry_code,count(pass_id) as cnt
from t1 left join t2
on t1.day=t2.capture_date
group by day,grantry_code;

2.generate_series function

function	Parameter type	Return type	describe
generate_series(start, stop)	int or bigint	int or bigint( The type is the same as the parameter )	Generate a numerical sequence , from start To stop, Step into one
generate_series(start, stop, step)	int or bigint	int or bigint( The type is the same as the parameter )	Generate a numerical sequence , from start To stop, Step by step to step
generate_series(start, stop, step_interval)	timestamp or timestamp with time zone	timestamp or timestamp with time zone( The type is the same as the parameter )	Generate a numerical sequence , from start To stop, Step by step to step

3. example

3.1 interval 1 God

select generate_series('2022-07-10'::date,'2022-07-17'::date,'1 day')

3.2  interval 1 Hours

select generate_series('2022-07-10'::date,'2022-07-17'::date,'1 hour')

 

3.3 interval 1 minute

select generate_series('2022-07-10'::date,'2022-07-17'::date,'1 min')