What is a database?
A database is a way of electronically storing collections of data in an organized manner. A database is controlled by a DBMS which is an acronym for Database Management System, DBMS's fall into two camps Relational or Non-Relational, the focus of this room will be on Relational databases, some common ones you'll come across are MySQL, Microsoft SQL Server, Access, PostgreSQL and SQLite. We'll explain the difference between Relational and Non-Relational databases at the end.
Within a DBMS, you can have multiple databases, each containing its own set of related data. For example, you may have a database called "shop". Within this database, you want to store information about products available to purchase, users who have signed up to your online shop, and information about the orders you've received. You'd store this information separately in the database using something called tables, the tables are identified with a unique name for each one. You can see this structure in the diagram below, but you can also see how a business might have other separate databases to store staff information or the accounts team.
What are tables?
A table is made up of columns and rows, a useful way to imagine a table is like a grid with the columns going across the top from left to right containing the name of the cell and the rows going from top to bottom with each one having the actual data.
Columns:
Each column, better referred to as a field has a unique name per table. When creating a column, you also set the type of data it will contain, common ones being integer (numbers), strings (standard text) or dates. Some databases can contain much more complex data, such as geospatial, which contains location information. Setting the data type also ensures that incorrect information isn't stored, such as the string "hello world" being stored in a column meant for dates. If this happens, the database server will usually produce an error message. A column containing an integer can also have an auto-increment feature enabled; this gives each row of data a unique number that grows (increments) with each subsequent row, doing so creates what is called a key field, a key field has to be unique for every row of data which can be used to find that exact row in SQL queries.
Rows:
Rows or records are what contain the individual lines of data. When you add data to the table, a new row/record is created, and when you delete data, a row/record is removed.
