What is SQL
Definition
SQL (Structured Query Language) is the language used to query, retrieve, and manipulate data stored in databases and data warehouses.
In Business Intelligence, SQL is how you ask questions of your data and get answers back.
What SQL Actually Means
Data stored in databases is not useful on its own.
To analyse it, you need a way to:
Select specific data
Filter it
Combine it
Aggregate it
SQL provides a structured way to do this.
Instead of manually searching through tables, you write queries that tell the system exactly what data you want.
Why SQL is Important in Business Intelligence
In a Business Intelligence system:
Data is stored in a data warehouse
Data models define relationships
Dashboards present the results
SQL sits in the middle.
It is used to:
Extract data from the warehouse
Transform it for analysis
Build datasets used in dashboards
Without SQL, it is difficult to work directly with data at scale.
What You Can Do with SQL
SQL allows you to:
Retrieve data from tables
Filter data based on conditions
Aggregate data (totals, averages, counts)
Join multiple tables together
Create new tables or views for analysis
These operations form the basis of most data analysis work.
A Simple Example
Imagine a table of orders with the following fields:
Order ID
Customer ID
Revenue
Date
A simple SQL query might answer:
Total revenue last month
Number of orders per day
Revenue by customer
Instead of manually calculating these, SQL does it instantly.
SQL and Data Modelling
SQL works closely with data models.
Because data is organised into tables and relationships, SQL can:
Join related tables together
Analyse data across different entities
For example:
Orders joined with customers
Orders joined with products
This allows for more meaningful analysis.
SQL vs BI Tools
Many BI tools allow users to build reports without writing SQL.
However:
SQL gives more control
SQL allows more complex analysis
SQL helps ensure accuracy
In practice, many dashboards are powered by SQL queries behind the scenes.
Common Misconceptions
“SQL is only for developers”
SQL is widely used by analysts and BI professionals, not just engineers.
“You need advanced SQL for BI”
Most BI work relies on a relatively small set of SQL concepts.
“BI tools replace SQL”
BI tools often generate SQL automatically, but understanding SQL helps you work more effectively.
Why SQL Matters
SQL makes it possible to:
Access data directly
Build reliable datasets
Perform accurate analysis
Understand how data is structured
It is one of the most important skills in Business Intelligence.
Summary
SQL is the language used to:
Query data
Analyse it
Transform it
In BI, it is the bridge between stored data and meaningful insights.