Also, surely if you left join to a table then if there's no matching row you get a null
value in your result set. So I'm not sure what the difference is between getting that
null because you store it in a column in the primary table, and deriving it by left
joining to a related table with no matching rows.
At 11:27 am +0000 16/3/06, Alec.Cawley@stripped wrote:
>As someone totally unread in the theory of databases, that seems unduly puritanical. I
> assume that what Date would propose is that you have another table (related by master key)
> in which, if you do not know something, you do not enter it. But this means that if you
> have 10 different pieces of potentially but not necessarily available information about a
> single master record (e.g. a person), you have to do a 10-way join in order to retrieve
> all the information about them. Replacing a theoretically ugly null flag with a 10 way
> join strikes me, as an engineer rather than a theoretician, the wrong side of the
> elegance/practicality trade-off.