Here is an actual set of data taken from the 1850 U. S. Federal census
- the first field is Dwelling number, the second is Family number, the
third is name. (There are additional fields such as age, sex,
occupation, etc.)
Row 1 - 124, 124, Monohan, James
Row 2 - , , Ammanda
Row 3 - , , Dean, Harley
Notice first of all that only the first row contains a family number
and a dwelling number. The second row contains only a first name. The
third row contains a last name but it is different than the last name
in row 1.
Here is my dilemma - If the key is for family or dwelling number, only
the first row would be retrieved. If the key is on last name and I
search for Dean, I'd get only row 3. If I search for Monohan I'd get
only row 1.
Any suggestions?
Wayne Dreier
Using OS X 10.3.7
Using RB 5.5.4
On Dec 28, 2004, at 3:37 PM, Phil Mobley wrote:
You need to keep track of your product serial numbers. Well a single
person can own more than one license or even multiple products. You
don't want to have all of the contact information for the person in
the registered products table, because (a) what if the contact info
changes, and (b) it takes up too much space (duplication of data).
You have a single table called 'Person' table contains a unique
identifier for each person (if you are using the RB DB, you can use
the '_rowid' column). Then in the 'Serials' table, have a column
'person_id' which is the same unique identifier used in the 'Person'
table.
Then to get all of the serial numbers registered to anyone who's last
name is 'Smith', here is the SQL (I am pretty sure this syntax is
correct and Will can correct me if I am wrong):
SELECT a.snumber FROM Serials A, Person P WHERE
a.person_id=p._rowid AND p.last_name='Smith'
This is called a Join where you take conditions from two tables to
generate the search results.
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