Question

I’m creating a program that besides what the program does it also provides statistic information. One thing I wanted to add was number of transactions per day and then have maybe a line chart that shows how the transactions changed by day(within a month), then by month, then by year. I just can’t really figure out how to convert that into a database that the program could pull that data and put it into a chart

Would be it be something like or is there something i’m missing:?

Day table;
(A.I)id, daynumber, dayofweek, numoftrans foreign keys: monthnumber , yearnumber

Month table

(A.I)id, monthnumber, nameofmonth, numoftrans

year table

(A.I)id, yearnumber, numberoftrans

Answer 1

All you need is a table that stores dates and number of transactions.

create table transactions_per_day (
  transaction_date date primary key,
  num_transactions integer not null check (num_transactions >= 0)
);

The number of transactions per month and per year can be done in a query with aggregate functions (SUM()) and a WHERE clause. For the total per month . . .

select
  extract(year from transaction_date) tr_year, 
  extract(month from transaction_date) tr_month, 
  sum(num_transactions) num_tr
from transactions_per_day
where transaction_date between '2013-01-01' and '2013-12-31'
group by tr_year, tr_month
order by tr_year, tr_month;

It often makes sense to create views for the monthly totals and the annual totals.

create view transactions_per_month as
select
  extract(year from transaction_date) tr_year, 
  extract(month from transaction_date) tr_month, 
  sum(num_transactions) num_tr
from transactions_per_day
where transaction_date between '2013-01-01' and '2013-12-31'
group by tr_year, tr_month
order by tr_year, tr_month;