Relational Database

What is a Relational Database Management System?

A relational database management system (RDBMS or just RDB) is a common type of database whose data is stored in tables.

You’ll find that most databases used in businesses these days are relational databases, as opposed to a flat file or hierarchical database.

Relational databases have the clout to handle multitudes of data and complex queries, whereas a flat file takes up more space and memory, and is less efficient.

So modern databases use multiple tables as standard. The data is stored in lots and lots of tables, or ‘relations’. These tables are divided into rows (records) and columns (fields).

See the data visualization in action:

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Much like the relationships between data in an entity’s relationship diagram, the tables in the relational database can be linked in several ways:

  • Characteristics of one table record may be linked to a record in another table
  • A table record could be linked to many records in another table
  • Many table records may be related to many records in another table.

What’s an SQL Query?

An SQL query is how you access the data. SQL stands for Structured Query Language.

Using an SQL query, you can create and delete, or modify tables, as well as select, insert, and delete data from existing tables.

Benefits of Relational Databases

If you want to design a data storage system that makes it easy to manage lots of information, and is scalable and flexible, the relational database is a good bet.

  • Manageability: for starters, an RDB is easy to manipulate. Each table of data can be updated without disrupting the others.
    You can also share certain sets of data with one group, but limit their access to others – such as confidential information about employees.
  • Flexibility: if you need to update your data, you only have to do it once – so no more having to change multiple files one at a time.
    And it’s pretty simple to extend your database. If your records are growing, a relational database is easily scalable to grow with your data.
  • Avoid Errors: there’s no room for mistakes in a relational database because it’s easy to check for mistakes against the data in other parts of the records. And since each piece of information is stored at a single point, you don’t have the problem of old versions of data clouding the picture.

Challenges of Relational Databases

  • Scalability: Because relational databases are built on a single server. This means, in order to scale, you’ll need to purchase more expensive hardware with more power, storage, and memory.
  • Performance: Rapid growth in volume, velocity, variety, and complexity of data creates even more complicated relationships. Relational databases tend to have a hard time keeping up, which can slow down performance.
  • Relationships: Relational databases don’t actually store relationships between elements, which makes understanding connections between your data reliant on other joins.