|
|
|
|
| |
There is another slight complication. One president (Jimmy Carter) has a "Jr." at the end of his name. Where does that go? Depending on the format in which names are printed, this president's name is displayed as "James E. Carter, Jr.," or "Carter, James E., Jr." The "Jr." doesn't associate with either first or last name, so we'll create another column to hold a name suffix. This illustrates how even a single value can cause problems when you're trying to determine how to represent your data. It also shows why it's a good idea to know as much as possible about the type of data values you'll be working with before you put them in a database. If you have incomplete knowledge of what your data look like, you may have to change your table structure after you've already begun to use it. That's not necessarily a disaster, but in general it's something you want to avoid.
Birthplace (city and state). Like the name, this too can be represented using a single column or multiple columns. It's simpler to use a single column, but as with the name, separate columns allow you to do some things you can't do easily otherwise. For example, it's easier to find records for presidents born in a particular state if city and state are listed separately.
Birth date and death date. The only special problem here is that we can't require the death date to be filled in because some presidents are still living. MySQL provides a special value NULL that means "no value," so we can use that in the death date column to signify "still alive."
|
|
|
|
|
|
| Link Partners: Asia florist, Flowers to India, Hongkong flowers, Site submit, Cheap web hosting, China florist |
|
