There are two types of keys in SQL: primary and foreign. These databases receive the “relational” qualifier because “related” tables are connected together by keys. In its simplest form, the relational data model is a collection of tables containing rows of data. Relational databases have been around for almost 50 years. In this article, I’ll discuss why primary keys are important, different types of keys you can use, and a primary key with values that are guaranteed to have never, ever been used in the entire universe (with a 1/10^37 chance of error). Because of its importance, we have to give special consideration to how we select our primary keys. The foundation for a table in a relational database is the primary key. Relational databases are highly intertwined, so one small change can have unexpected, cascading effects.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |