SQL Grid Ranges

Question

I have a list of customers with an x and y co-ordinate for each between -50 and 50 for each. I need to calculate the number of customers in each 10x10 grid square but don't know how I can group customers by a range in two columns. The Customer table has a customerID, customer_x and customer_y column. I've managed to get the result for a single column using

SELECT 10 * ( customer_x / 10 ) AS start_range, 10 * ( customer_x / 10 ) + 9 AS end_range, count(*) AS COUNT FROM t_customer GROUP BY customer_x / 10

I found this here, but can't work out how to get this working with a 2 dimensional range. I've started writing out a case for each grid-square using Select * from customer where (customer_x, customer_y) between (-50,-50) and (-50,-40) and so on, but there's 100 in total and I'm assuming there's a more efficient way? I'm using SQLite3. Any help would be really appreciated.

I forgot to add, it actually only needs to show the grid square with the highest number of customers, so there may be a far easier way of doing this?

Answer 1

GROUP BY customer_x / 10, customer_y / 10