4 table query / join. getting duplicate rows
- by Horse
So I have written a query that will grab an order (this is for an ecommerce type site), and from that order id it will get all order items (ecom_order_items), print options (c_print_options) and images (images). The eoi_p_id is currently a foreign key from the images table.
This works fine and the query is:
SELECT
eoi_parentid, eoi_p_id, eoi_po_id, eoi_quantity,
i_id, i_parentid,
po_name, po_price
FROM ecom_order_items, images, c_print_options WHERE eoi_parentid = '1' AND i_id = eoi_p_id AND po_id = eoi_po_id;
The above would grab all the stuff I need for order #1
Now to complicate things I added an extra table (ecom_products), which needs to act in a similar way to the images table. The eoi_p_id can also point at a foreign key in this table too. I have added an extra field 'eoi_type' which will either have the value 'image', or 'product'.
Now items in the order could be made up of a mix of items from images or ecom_products. Whatever I try it either ends up with too many records, wont actually output any with eoi_type = 'product', and just generally wont work. Any ideas on how to achieve what I am after? Can provide SQL samples if needed?
SELECT
eoi_id, eoi_parentid, eoi_p_id, eoi_po_id, eoi_po_id_2, eoi_quantity, eoi_type,
i_id, i_parentid,
po_name, po_price, po_id,
ep_id
FROM ecom_order_items, images, c_print_options, ecom_products WHERE eoi_parentid = '9' AND i_id = eoi_p_id AND po_id = eoi_po_id
The above outputs duplicate rows and doesnt work as expected. Am I going about this the wrong way? Should I have seperate foreign key fields for the eoi_p_id depending it its an image or a product?
Should I be using JOINs?
Here is a mysql explain of the tables in question
ecom_products
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| ep_id | int(8) | NO | PRI | NULL | auto_increment |
| ep_title | varchar(255) | NO | | NULL | |
| ep_link | text | NO | | NULL | |
| ep_desc | text | NO | | NULL | |
| ep_imgdrop | text | NO | | NULL | |
| ep_price | decimal(6,2) | NO | | NULL | |
| ep_category | varchar(255) | NO | | NULL | |
| ep_hide | tinyint(1) | NO | | 0 | |
| ep_featured | tinyint(1) | NO | | 0 | |
+-------------+--------------+------+-----+---------+----------------+
ecom_order_items
+--------------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+-------------+------+-----+---------+----------------+
| eoi_id | int(8) | NO | PRI | NULL | auto_increment |
| eoi_parentid | int(8) | NO | | NULL | |
| eoi_type | varchar(32) | NO | | NULL | |
| eoi_p_id | int(8) | NO | | NULL | |
| eoi_po_id | int(8) | NO | | NULL | |
| eoi_quantity | int(4) | NO | | NULL | |
+--------------+-------------+------+-----+---------+----------------+
c_print_options
+------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+----------------+
| po_id | int(8) | NO | PRI | NULL | auto_increment |
| po_name | varchar(255) | NO | | NULL | |
| po_price | decimal(6,2) | NO | | NULL | |
+------------+--------------+------+-----+---------+----------------+
images
+--------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+--------------+------+-----+---------+----------------+
| i_id | int(8) | NO | PRI | NULL | auto_increment |
| i_filename | varchar(255) | NO | | NULL | |
| i_data | longtext | NO | | NULL | |
| i_parentid | int(8) | NO | | NULL | |
+--------------+--------------+------+-----+---------+----------------+
