Java Practices->Remember the basics of database design

Remember the basics of database design

Remember the basics of database design, or normalization:

each table has a primary key
the job of the primary key is to uniquely identify records, not to store business data; any use of business data in a primary key is a dangerous practice, since any changes to such data will have large ripple effects
a good deal of data normalization is summed up by the memorable phrase: "a table stores facts about the key, the whole key, and nothing but the key"
relations between tables are implemented using foreign keys, where one table refers to the primary key of another table
almost all relations are 1..N
1..1 relations are permitted, but need a reason to not be a 1..N relation (this reason is usually a performance optimization)
cross references between tables A and B are implemented by a third table C, which contains two foreign keys, one for each of the primary keys of tables A and B

Database performance:

Connection pools can improve performance
using PreparedStatement instead of Statement can improve performance as well
fetching data with SELECT statements can often account for the great majority of activity (often 95% or more). For apps that focus on processing transactions, the relative number of SELECTs is usually lower.