Database Structure

If you have ever been to a sandwich shop, you have seen a long counter with containers of various lengths and sizes. Each of these containers has a specific purpose— some hold meat, others hold cheese, and others hold vegetables; there are even containers for the...

ANSI Standard

Because there are several different database vendors, there are a set of standards that must exist across the database platforms. ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) and...

Syntax

Syntax is the technical requirement the query must have to return the results you want. If the query is not properly formed, a result cannot be given. Think of proper sentence structure—should a question not end with a question mark? Syntax is similar to grammar...

Tables

A SQL table is a container for the database to hold your data. A kitchen table in my house might only hold a plate, a fork, and a cup. A table set for a fine French restaurant might hold several plates, a bowl, wine glasses, napkins, candles, and more silverware than...

Primary Key

PRIMARY KEYS In our relational system we want a way to make each row unique so we can tell them apart and ensure when we query the table we will be able to identify each row. To assist us in this we use a primary key—a column or combination of columns that contain...