How to categorize customer through MYSQL query? - mysql

Question

I am finding difficulty in writing mysql query to categorize my customers. I am categorizing customers based on number of hits on my website.like
New customer with one hits.
New customer with multiple hits.
Old customer
My Log table schema is as follows
Unique customer ID, Current Date, Subscribed, Hits Count
To categorize customer how can I compare current date customer logs with all the previous date logs through single query

Answer 1

It's not clear from your description, is customer_id unique?
Or is it the tuple (customer_id,current_date,subscribed,hits_count) that is unique?
If customer_id is unique, then something like this will return the specified result:
SELECT t.customer_id
, CASE
WHEN t.hits_count = 1 AND t.current_date = DATE(NOW())
THEN 'New customer with one hits.'
WHEN t.hits_count > 1 AND t.current_date = DATE(NOW())
THEN 'New customer with multiple hits.'
ELSE 'Old customer'
END AS category
FROM mytable t
If customer_id is not unique, then one way (but not the most efficient way) to get the specified result:
SELECT t.customer_id
, CASE
WHEN t.total_hits_count = 1 AND t.min_current_date = DATE(NOW())
THEN 'New customer with one hits.'
WHEN t.total_hits_count > 1 AND t.min_current_date = DATE(NOW())
THEN 'New customer with multiple hits.'
ELSE 'Old customer'
END AS category
FROM ( SELECT h.customer_id
, MIN(h.current_date) AS min_current_date
, SUM(h.hits_count) AS total_hits_count
FROM mytable h
GROUP BY h.customer_id
) t
The inline view aliased as t gets us unique values for customer_id, along with the earliest current_date, and the total of the hits_count. (You can run just the query inside the parens to verify it's returning the desired result.) The outer query is identical to the first query, with just some renamed columns.
The inline view isn't necessary, you could get an equivalent result (more efficiently) with something like this:
SELECT t.customer_id
, CASE
WHEN SUM(t.hits_count) = 1 AND MIN(t.current_date) = DATE(NOW())
THEN 'New customer with one hits.'
WHEN SUM(t.hits_count) > 1 AND MIN(t.current_date) = DATE(NOW())
THEN 'New customer with multiple hits.'
ELSE 'Old customer'
END AS category
FROM mytable t
GROUP BY t.customer_id
NOTE There's some corner cases that will cause customer_id to be categorized as 'Old customer', such as SUM(t.hits_count) < 1, or t.current_date IS NULL, etc.
To specifically test for a row with a current_date before today's date, make a specific test for that in the CASE expression:
SELECT t.customer_id
, CASE
WHEN SUM(t.hits_count) = 1 AND MIN(t.current_date) = DATE(NOW())
THEN 'New customer with one hits.'
WHEN SUM(t.hits_count) > 1 AND MIN(t.current_date) = DATE(NOW())
THEN 'New customer with multiple hits.'
WHEN MIN(t.current_date) < DATE(NOW())
THEN 'Old customer'
ELSE 'Some other category'
END AS category
FROM mytable t
GROUP BY t.customer_id
NOTE
I assumed that the current_date column was of type DATE, and not DATETIME or TIMESTAMP. If that column also includes a time component which is not equal to midnight 00:00:00, then the equality comparison to DATE(NOW()) is not going to return TRUE whenever that time component is not midnight.
In that case, we'd prefer to check a range of datetime values, replacing
... AND t.current_date = DATE(NOW())
with something like this:
... AND t.current_date >= DATE(NOW()) AND t.current_date < DATE(NOW()) + INTERVAL 1 DAY