Summary
In this hour, you got a brief introduction to the SQL language and the relational database. SQL is the standard language for communicating with any relational database. It is important to first understand what comprises the relational database, identify the key elements, know what data looks like, and understand how the data in the relational database is related to other data within the database. When you fully grasp these concepts, your journey into the SQL language will take flight sooner and the concepts in this book will make more sense. The goal of this hour was to introduce some basic database concepts and give you a foundation for thinking about data at a higher level.
Simply put, a relational database is a database that is logically organized into multiple tables that might or might not be related to one another. A table consists of one or more columns, or fields, and one or more rows of data. A table can have just a few rows of data or millions upon millions of rows of data. Tables are related through common columns, or fields, that are defined in a relational database using constraints such as primary keys and foreign keys. These keys are built-in features of a relational database that maintain referential integrity within the database. This is the key to the relational database and one of the main components of SQL. Subsequent chapters cover all these concepts in examples and hands-on exercises.