SQL - % split between sale types - sql

Question

I need some SQL help.
I have a table where I'm trying to get the % split between online sales and POS sales. Below is the query I have written and the screenshot is what I get, but I don't know how to proceed from there.
I need a third column that shows the percentage split between online sales and POS sales.
That would be (POS/(POS+ONLINE))*100 and (ONLINE/(POS+ONLINE))*100
Here's my current query
SELECT
CASE
WHEN saleschannel = 1 THEN 'ONLINE'
WHEN saleschannel = 6 THEN 'ONLINE'
WHEN saleschannel = 7 THEN 'ONLINE'
WHEN saleschannel = 8 THEN 'ONLINE'
ELSE 'POS'
END AS CHANNEL,
COUNT(*) AS TICKET_QTY
FROM performancesales
WHERE salesdate BETWEEN '2022-08-01' AND '2023-01-31'
AND saleschannel IN ('1','6', '7', '8', '14')
GROUP BY CHANNEL
ORDER BY 2;
Thanks to Aaron his query was right and helped me. I have rewritten it to make it a bit faster. This is my final code
SELECT
channel,
COUNT(*) AS ticket_qty,
CAST(100.0 * COUNT(*) / SUM(COUNT(*)) OVER() AS DECIMAL(10,2)) AS percentage_split
FROM (
SELECT
CASE
WHEN saleschannel IN ('2','5','7') THEN 'ONLINE'
WHEN saleschannel IN ('0','1','4','6','8') THEN 'POS'
ELSE 'OTHER - (AGGREGATOR)'
END AS channel,
1 AS ticket
FROM performancesales
WHERE
salesdate BETWEEN '2022-08-01' AND '2023-01-31'
AND saleschannel IN ('0','1','2','3','4','5','6','7','8')
) t
GROUP BY channel;

Answer 1

I thnk this will do it,
WITH CTE AS
(
SELECT
CASE
WHEN saleschannel = 1 THEN 'ONLINE'
WHEN saleschannel = 6 THEN 'ONLINE'
WHEN saleschannel = 7 THEN 'ONLINE'
WHEN saleschannel = 8 THEN 'ONLINE'
ELSE 'POS'
END AS CHANNEL,
COUNT(*) AS TICKET_QTY
FROM
performancesales
WHERE
salesdate BETWEEN '2022-08-01' AND '2023-01-31'
AND
saleschannel IN ('1','6', '7', '8', '14')
GROUP BY
CHANNEL
)
SELECT
CHANNEL
,TICKET_QTY
,CAST(TICKET_QTY AS DECIMAL(10,2)) / SUM(TICKET_QTY) OVER() AS [Percentage]
FROM
CTE
Wrap the original query up as a CTE (Common Table Expression) [you can call it whatever you like]. the SUM()OVER() will calculate the total sum of the dataset for each row returned. You also have to convert one of the values to a decimal otherwise you will be dividing and integer by an integer and will get an integer result. If you need more precision, do DECIMAL (10,6)

Answer 2

You can do this using filtered aggregation.
select
count(*) filter (where saleschannel in ('1','6', '7', '8')) as pos_qty,
count(*) filter (where saleschannel = '14') as online_qty,
count(*) filter (where saleschannel in ('1','6', '7', '8'))::numeric / count(*) * 100 as pos_percentage,
count(*) filter (where saleschannel = '14')::numeric / count(*) * 100 as online_percentage
FROM performancesales
WHERE salesdate BETWEEN '2022-08-01' AND '2023-01-31'
AND saleschannel IN ('1','6', '7', '8', '14');