How to search for count of customers in SQL database? - sql

Question

I have an SQL table named "accounts" with the following columns:
registration_date
account_id
and have another SQL table named "revenue" with the following columns:
account_id
revenue_month
sales_revenue
What I am trying to achieve is to get the following:
Get a count of customers that registered between Jan and Dec 2017, and a count of how many of them bought something in 2017 (ie. sales_revenue more than 0).
I am very new to SQL and I tried the following but I couldn't do it.
SELECT COUNT account_id
FROM accounts
WHERE registration_date BETWEEN #01/01/2017# AND #12/31/2017#;
should give me the number of accounts that were registered in 2017?
and then
SELECT COUNT account_id
FROM revenue
WHERE sales_revenue > 0;
should give me the number of accounts that had a revenue of more than 0?
What am I missing? I would appreciate any help.
THANKS!

Answer 1

Try this out:
select count(account_id) as total,
sum(case when sales_revenue > 0 then 1 else 0 end) as sales_rev
FROM accounts
WHERE registration_date BETWEEN #01/01/2017# AND #12/31/2017#;
Let me know in case of any queries.

Answer 2

SELECT
COUNT(DISTINCT accounts.account_id)
FROM
accounts, revenue
WHERE
accounts.registration_date BETWEEN #01/01/2017# AND #12/31/2017#
AND
revenue.revenue_month BETWEEN #01/2017# AND #12/2017#
AND
accounts.account_id = revenue.account_id
AND
sales_revenue > 0

Answer 3

Oracle (again). Your database might use different functions.
Presuming that REGISTRATION_DATE is of a DATE datatype (and yes, it should be), then this might do the job:
select count(*)
from accounts
where extract(year from registration_date) = 2017;
The same goes for revenue - presuming that REVENUE_MONTH is DATE. If it is not, what is it?
select count(distinct account_id)
from revenue
where extract(year from revenue_month) = 2017
having sum(sales_revenue) > 0;

Answer 4

Try the following
Get a count of customers that registered between Jan and Dec 2017
SELECT COUNT (account_id)
FROM accounts
WHERE registration_date BETWEEN '01-JAN-2017' AND '12-DEC-2017'
and a count of how many of them bought something in 2017 (ie. sales_revenue more than 0).
SELECT COUNT (account_id)
FROM revenue
WHERE sales_revenue > 0
AND registration_date BETWEEN '01-JAN-2017' AND '12-DEC-2017'
The above is Oracle, your database would be something similar.

Answer 5

If you post a SQLFiddle, sample data and expected results, you'll get better answers...
You are missing a join.
Table accounts tells you who registered in the date range you care about, and table revenue tells you what they bought.
Not every account bought something, so you need an outer join.
As you only want to count the number of accounts that bought something, rather than the number of transactions, you have to use a distinct count. Not supported on every platform.
You want something like:
SELECT COUNT (a.*), count(distinct r.account_id)
FROM accounts a
outer join revenue r
on a.account_id = r.account_id
WHERE a.registration_date BETWEEN #01/01/2017# AND #12/31/2017#
and r.revenue_Month between '01/2017' and '12/2017'

Answer 6

This gives you all customers who registered in 2017 along with the information whether they bought something in 2017:
select
account_id,
case when exists
(
select *
from revenue r
where r.account_id = a.account_id
and r.sales_revenue > 0
and r.revenue_month like '%2017%'
) then 1 else 0 end as has_bought_in_2017
from accounts a
where year(registration_date) = 2017;
(You may want to change the LIKE clause; I don't know how your revenue_month is built.)
Now use this query to get the counts:
select
count(*) as registered_in_2017,
sum(has_bought_in_2017) as and_have_bought_in_2017
from (<above query>) q;

Answer 7

SELECT COUNT(account_id)
FROM accounts
WHERE registration_date BETWEEN '01/01/2017' AND '12/31/2017';
This will give you the count of account id who has registered in between 01/01/2017 AND 12/31/2017
SELECT COUNT(account_id)
FROM revenue
WHERE sales_revenue > 0;
This will give you the number of account id's who has sales_revenue greater than zero.
If you want the number of accounts between 01/01/2017 AND 12/31/2017 and
sales_revenue > 0 then:
select count(account_id)
from accounts a,revenue r
where a.registration_date BETWEEN '01/01/2017' AND '12/31/2017'
and r.sales_revenue > 0;