A badly designed database has the following problems:
- Related data is scattered over various
A change must be updated at many places.
It's possible that the information is only half present, it's there in one table, but missing in another one.
- Data is inconsistent or ambiguous (poly interpretable).
- The database is unnessessary complex, hacked with lots of tricks.
The database designer done unnceccessary complex things, where it could have been done so much easier.
- The database has 'hidden' information, for example by the sequence of rows in a table.
- The database is slow, inflexible, hard to extend and can not handle all real life situations.