[thelist] SQL query statement help
rudy
r937 at interlog.com
Mon Dec 9 18:39:00 CST 2002
nice design, chris, very nice examples
one wee point (and i admit it's more style than substance)
in the item table, you have
> -> item_type_id (foreign key from item_types)
instead of from, i prefer to say to
it's a foreign key to the item_types table
what you intended was, and i'm guessing, is that the values in this column
in the item table are values that originated in the primary key in the
item_type table, and that would be correct
in practice, this is borne out by the need to create the primary key in the
item_type table first, after which it can be used in foreign keys
to me, the key question for each item is "which item type is this item?"
the answer is "that one over there"
in other words, the foreign key points to the primary key
this is reinforced by the syntax FOREIGN KEY foo REFERENCES bar
this in turn reminds you (well, it does me, anyway) that you can have
multiple foreign keys pointing to the same primary key
multiple iteme can reference the same item_type
the foreign key is in the child, and points to the parent
rudy
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