On Wed, Sep 15, 2021 at 12:55 AM Steve Litt wrote:
> Rich, could you please elaborate on SQL queries being based on sets? I
> never thought of it that way, and would like to hear your related
> thoughts.
I'll take a crack at this. Going through the setup will require a
little patience, but I thi
On Wed, 15 Sep 2021, Steve Litt wrote:
Rich, could you please elaborate on SQL queries being based on sets? I
never thought of it that way, and would like to hear your related
thoughts.
SteveT,
In the 1980s, when there were computer magazines such as Byte and Database
Administrator (among man
>
> Rich, could you please elaborate on SQL queries being based on sets?
> I
> never thought of it that way, and would like to hear your related
> thoughts.
>
When Codd & Date elaborated the relational model, it was based on set
theory.
You have sets of data. Is there a relationship between the
I agree.
I've always thought SQL was a great example of set theory put into practice.
You specify the elements (select items) and conditions (where clause) to return
the (sub)sets you want.
Spatial data is also about sets - a polygon is theoretically defined as the set
of points contained by a
Oh, yeah, wow. Big topic.
My original post in the series is in significant part about how SQL hides this
sort of thing from you.
A table is a set: a set of true facts, all having the same structure, so you
can operate on all of them with any operation on the individual rows.
Multiple tables,
