|
In this section, we will only discuss
inner joins, and equijoins,
as in general, they are the most useful.
For more information, try the SQL
links at the bottom of the page.
Good database design
suggests that each table lists data
only about a single entity,
and detailed information can be obtained
in a relational database, by using
additional tables, and by using a
join.
First, take a look
at these example tables:
AntiqueOwners
| OwnerID |
OwnerLastName |
OwnerFirstName |
| 01 |
Jones |
Bill |
| 02 |
Smith |
Bob |
| 15 |
Lawson |
Patricia |
| 21 |
Akins |
Jane |
| 50 |
Fowler |
Sam |
Orders
| OwnerID |
ItemDesired |
| 02 |
Table |
| 02 |
Desk |
| 21 |
Chair |
| 15 |
Mirror |
Antiques
| SellerID |
BuyerID |
Item |
| 01 |
50 |
Bed |
| 02 |
15 |
Table |
| 15 |
02 |
Chair |
| 21 |
50 |
Mirror |
| 50 |
01 |
Desk |
| 01 |
21 |
Cabinet |
| 02 |
21 |
Coffee Table |
| 15 |
50 |
Chair |
| 01 |
15 |
Jewelry Box |
| 02 |
21 |
Pottery |
| 21 |
02 |
Bookcase |
| 50 |
01 |
Plant Stand |
|
