Re: becoming unconfused

[trogers]

I just came from the bookstore where I perused "Mastering MySQL 4".  
Specifically, I wanted to know how to specify a Foreign Key.  After a 
thorough, albeit short lived search, and reading every page the index 
on "Foreign Key" pointed to, I deduced that all one needs do is put the 
blasted field (primary key from other table) into the "many" (re 
:appropriate) table.  That there was no "identifier" like there is a 
Primary Key.

Ok, my last puzzlement --for now-- is, let me illustrate:

table1                          table2
studentID -->PK      classID -->PK
student_name         class_name
                                  studentID  (foreign key)
Simple (yes I'm slow, yes it's a problem) question:  how does the 
studentID field in table2 get populated?

Thanks in Advance,
Ted
On Sunday, June 1, 2003, at 06:32 PM, Becoming Digital wrote:

The way I was taught, in my limited education, was simply to have, 
say,
the people_id also appear in table2 as a Foreign Key, that tis would
serve to relate the tables.  Now I've been advised that the way to do
this is NOT like that, but to have a third, linking, table
In my opinion, you've been wrongly advised.  I would follow your 
original
instinct and use a one->many relationship for people to machines.  
Using a third
table is just going to complicate things and goes against the concepts 
of
normalized data.

Edward Dudlik
Becoming Digital
www.becomingdigital.com
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: "Becoming Digital" <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Sunday, 01 June, 2003 15:59
Subject: Re: Inserting data?
I'd be glad to share.. you mean what the db is supposed to be?  Ok,
there are 3 tables:
table1 = people, people_id = primary key
table2 = machines, machines_id = primary key
One person can have many machines, one machine can only be assigned to
one person.
The way I was taught, in my limited education, was simply to have, say,
the people_id also appear in table2 as a Foreign Key, that tis would
serve to relate the tables.  Now I've been advised that the way to do
this is NOT like that, but to have a third, linking, table where there
are 2 fields: one is the people_id (primary key from table1) and the
other is the machines_id (primary key from table2).
I was asking how to write a SQL statement to populate that third table
from the data already in/from the other 2.
Any other comments about this are welcome.

Thanks,
Ted
On Sunday, June 1, 2003, at 10:53 AM, Becoming Digital wrote:

You need a constraint on the data to be inserted into the second
table.  Care to
share what that is supposed to be?
Edward Dudlik
Becoming Digital
www.becomingdigital.com
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, 01 June, 2003 03:17
Subject: Inserting data?
I have a table, in the table is a field called  name_id; in a second
table (a linking table) I also have the field name_id, this should be
the same/reference the same name_id as in the first table.
The first table is fully populated.  How do write a SQL statement to
get the data from the name_id field of table1 into the name_id field 
of
table2?

(I'll do this and find out after if it actually references the same
data!  So, if it doesn't at least I'll have learned the proper SQL
statement. :)
Thank you,
Ted Rogers


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