Check out the InnoDB reference in the MySQL manual. http://www.mysql.com/doc/en/InnoDB.html
Here's the section Foreign Key Constraints http://www.mysql.com/doc/en/InnoDB_foreign_key_constraints.html Good luck. Edward Dudlik Becoming Digital www.becomingdigital.com ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, 01 June, 2003 21:48 Subject: Re: becoming unconfused 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 -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
