What is a Database?

Make the Leap from a Spreadsheet to a Database

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Databases offer an organized mechanism for storing, managing and retrieving information. They do so through the use of tables. If you’re familiar with spreadsheets like Microsoft Excel, you’re probably already accustomed to storing data in tabular form. It’s not much of a stretch to make the leap from spreadsheets to databases. 

Databases vs. Spreadsheets

Databases are far better than spreadsheets for storing a lot of data, however, and for manipulating that data in various ways.

You encounter the power of databases all the time in your daily life.

For example, when you log into your online banking account, your bank first authenticates your login using your username and password, and then displays your account balance and any transactions. It is the database operating behind the scenes that evaluates your username and password combination, and then provides you access to your account. The database filters your transactions to display them by date or type, as you request.

Here are just a few of the actions that you can perform on a database that would be difficult, if not impossible, to perform on a spreadsheet:

 

  • Retrieve all records that match certain criteria
  • Update records in bulk
  • Cross-reference records in different tables
  • Perform complex aggregate calculations

Let's consider some of the basic concepts behind a database. 

The Elements of a Database

A database is made up of multiple tables.

Just like Excel tables, database tables consist of columns and rows. Each column corresponds to an attribute, and each row corresponds to a single record. Each table must have a unique name in a a database.

For example, consider a database table that contains names and telephone numbers. You would probably set up columns named “FirstName,” “LastName” and “TelephoneNumber.” Then you would simply start adding rows underneath those columns that contain the data.

In a table of contact information for a business with 50 employees, we’d wind up with a table that contains 50 rows.

An important aspect of a table is that each must have a primary key column, so that each row (or record) has a unique field to identify it. 

The data in a database is further protected by what are called constraints. Constraints enforce rules on the data to ensure its overall integrity. For example, a unique constraint ensures that a primary key cannot be duplicated. A check constraint controls the type of data you can enter — for example, a Name field can accept plain text, but a social security number field must include a specific set of numbers. Several other types of constraints exist, as well.

One of the most powerful features of a database is the ability to create relationships between tables using foreign keys. For example, you might have a Customers table and an Orders table. Each customer can be linked to an order in your Orders table.The Orders table, in turn, might be linked to a Products table. This kind of design comprises a relational database, and simplifies your database design so that you can organize data by category, rather than trying to put all the data into one table, or just a few tables.

A Database Management System (DBMS)

A database simply holds data. To make real use of the data, you need a Database Management System (DBMS). A DBMS is the database itself, along with all the software and functionality to retrieve data from the database, or to insert data. A DBMS create reports, enforces database rules and constraints, and maintains the database schema. Without a DBMS, a database is just a collection of bits and bytes with little meaning.