在MySQL中查询多个表

Question

I am trying to fetch data from multiple tables depending on what is selected in a dropdown menu. My dropdown menu consists of a list of ID's (001, 002, etc).

Once a user selects one of them, I am using AJAX to dynamically fetch data depending on what was selected. I was able to fetch a single value depending on what was selected but having problems when multiple tables are involved.

My tables are set up like this:

Inventory table:

inven_ID (primary)
cost
description

Order table:

order_ID(primary)
orderdesc

Sale table:

inven_ID
order_ID
quantity
primary(inven_ID,order_ID)

My query is as follows:

$QRY = "SELECT 
          inven_ID, 
          order_ID, 
          cost, 
          description 
        FROM 
          Inventory, 
          Order, 
          Sale 
        WHERE Inventory.inven_ID = Sale.inven_id 
        AND Sale.order_ID = Order.order_ID 
        AND Order.order_ID ='".$q."'";

The $q represents the value from the dropdown menu (which I checked is valid). I am getting the error Column ' inven_ID ' in field list is ambiguous. Basically, when they select some order id from the drop down (say 001), it looks for order_ID in my Order table, and fetches the inven_ID/cost/description of that particular order ID.

Eg. if someone ordered parts xy, yz, xyz for cost 10,20,30.

Selecting 001 would bring up:
001 xy 10
001 yz 20
001 xyz 30

I think I am not joining tables properly since the error says its ambiguous.

Any help on this?

edit: yes that fixed the problem, quite obvious that I did not catch it.

Answer 1

In the column list of your select, you just need to specify which inven_ID you want to retrieve. For instance:

SELECT Inventory.inven_ID, ...

Answer 2

The error is pretty obvious. inven_ID is ambiguous because you have it in Sale and in Inventory . Use a specifier like Sale.inven_ID or Inventory.inven_ID .