Re: DB Design Concepts

actualy i'm not soo smart.. > Max Thayer wrote: > > I'm using MySQL 5.x InnoDB engine, transactional tables. I have a > > conceptual design question. If I have a two columns 'a' and 'b', a is > > the primary key, and b is a type double, in table 1 (T1) for which > > column b will have many NULL values, do I leave it with an allow null > > constraint on the column or pull the column and place it into table 2 > > (T2) with a foreign key, making a simple optional one-to-one > > relationship. Over the course of time, as the table fills with records, > > will a column w/ many NULL values have a detrimental effect on > > performance or maintenance with regards to the DB? Am I missing > > something here in DB design 101, by leaving the column in the T1 and > > knowing it will only be populated 7% of the time; what are the major > > implications based on the RDBMS and engine I'm using? can we see your table?? u can use my way for your problem. if you have access.. the lowest is fine. I create the table from there and then i use relationship. > What kind of queries are you going to be running? Where you need both > columns all the time? i ask same things.. hope my zip can help u