Cliff
By adding the 'null' to the 'purchase_order_id' in the product_lots table,
you automatically achieve it - that is, if the field is declared as Null,
foreign key constraint is applicable only if it is non-null and a null
value will automatically skip validation for foreign key.
Another
Thank you, Sundar.
I understand. This solution means I relinquish the foreign key constraint
on the product_lots table.
It does seem simpler than using another table for raw materials.
No third alternative, I guess...
On Friday, April 20, 2012 2:37:38 AM UTC-4, Sundar wrote:
Cliff
By
Not sure if 'relinquish' is the right word since the foreign constraint is
going to be enforced if you enter a value for the PO. (May be my statement
was a little confusing).
Please see the example:
Create Table t1(a int primary key)
Create table t2 (b int primary key, ba null references
I don't understand what you are trying to achieve, but whatever it is, you
are doing it wrong; your model should be:
db.define_table('A', Field('name'))
db.define_table('B', Field('name'), Field('id_from_table_a', 'reference A'))
# alternatively:
# db.define_table('B', Field('name'),
nick,
Thanks for the response.
Here's a longer explanation.
Two applications, one is purchasing, the other is production.
Purchasing has two tables, purchase_orders and product_lots. It's a
one-to-may relationship; a purchase order can have many product lots. So
we get:
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