Lets say I have three different MySQL tables:
Table products
:
id | name
1 Product A
2 Product B
Table partners
:
id | name
1 Partner A
2 Partner B
Table sales
:
partners_id | products_id
1 2
2 5
1 5
1 3
1 4
1 5
2 2
2 4
2 3
1 1
I would like to get a table with partners in the rows and products as columns. So far I was able to get an output like this:
name | name | COUNT( * )
Partner A Product A 1
Partner A Product B 1
Partner A Product C 1
Partner A Product D 1
Partner A Product E 2
Partner B Product B 1
Partner B Product C 1
Partner B Product D 1
Partner B Product E 1
Using this query:
SELECT partners.name, products.name, COUNT( * )
FROM sales
JOIN products ON sales.products_id = products.id
JOIN partners ON sales.partners_id = partners.id
GROUP BY sales.partners_id, sales.products_id
LIMIT 0 , 30
but I would like to have instead something like:
partner_name | Product A | Product B | Product C | Product D | Product E
Partner A 1 1 1 1 2
Partner B 0 1 1 1 1
The problem is that I cannot tell how many products I will have so the column number needs to change dynamically depending on the rows in the products table.
This very good answer does not seem to work with mysql: T-SQL Pivot? Possibility of creating table columns from row values
Best Answer
Unfortunately MySQL does not have a
PIVOT
function which is basically what you are trying to do. So you will need to use an aggregate function with aCASE
statement:See SQL Demo
Since you do not know the Products you will probably want to perform this dynamically. This can be done using prepared statements.
With dynamic pivot tables (transform rows to columns) your code would look like this:
See SQL Demo
It's probably worth noting that
GROUP_CONCAT
is by default limited to 1024 bytes. You can work around this by setting it higher for the duration of your procedure, ie.SET @@group_concat_max_len = 32000;