In the previous chapter, we learned not only how to create a database but how to do it well. Well-considered table design, column constraints, and relationships will really shine once we start putting data into the tables. With our strong table design and the well-thought-out relationships between them, we will be able to join efficiently and easily. When a piece of data needs to be changed (e.g., a customer address), we only need to change it in one place rather than several. When a bad piece of data comes in, hopefully we have set enough sensible constraints to prevent it from entering the database.
In this chapter, we will learn how to
UPDATE records. Fortunately, writing operations like these is much simpler than writing
These SQL write operations do not have to be done by a human. Software (written in Java, Python, or other coding languages) will often generate and execute SQL statements to read and write data the same way a human would, but much more efficiently. Although this is beyond the scope of this book, coding languages will be touched on in the next chapter if that is pertinent to you.
In a relational database, data only exists if the database first receives records. The
INSERT statement does just that and inserts a record into the database. You can pick what fields to populate in the record, and the rest of the fields will be null or use a default value.
First, we will
ATTENDEE record ...