Databases use keys to store, sort and compare relationships between records. There are three different types of keys: primary keys, candidate keys and foreign keys. When setting up a database table, the software will ask you to set up a primary key that will be responsible for identifying each record in the table. You might not think much about choosing a primary key, but this is actually a very big and important decision.
Why are Primary Keys a Big Deal?
Designing a new database comes with many choices, and selecting a primary key is one of them. In fact, it’s one of the most important. The purpose of a primary key is to implement a relationship between two tables. Without a primary key, relational databases wouldn’t exist.
Even though a primary key might sound a bit unusual, we use them in everyday life without realizing it. Student IDs are an example of a primary key. Students are uniquely identified by these numbers, but the numbers don’t mean anything outside the school.
Below are the advantages to using primary keys.
- Serves as a common link field between tables
- Speeds up queries, searches and sort requests
- Only valid records will be in your table
- No duplicates will be added
- MS Access shows data in order of the primary key
How to Choose a Primary Key
Primary keys should be 100% unique. You can generally turn to your database for the answers you’re looking for. In many cases, people will use the database management system to generate a unique identifier. This way, you’ll have a reliable system for referencing individuals or things in your database, but they won’t have meaning outside the system.
Good primary keys are usually short and include all numbers. They avoid using special characters or a combination of uppercase and lowercase letters. Some things that do NOT make good primary keys are zip codes, email addresses and Social Security numbers. Primary keys should not contain null values and must contain a unique value for each row of data.
Good database design starts by having a good primary key. You can learn more about finding the best primary key for your database in this article, or call Arkware. Our pros will be happy to walk through the steps with you.