How can you optimize your SQL queries for performance and readability?

Imagine that you are working for a retail company and want to analyze the sales data to gain insights and make informed decisions. You will be using SQL queries to extract the necessary information from the company’s database. 

Here are some best practices to optimize your SQL queries for performance and readability:

Use proper indentation and formatting: 

Don’t do this: 

Why it’s bad:

• The query is written in a single line, making it difficult to read and understand. 

Do this instead:

  

 

Use JOINs instead of subqueries: 

Don’t do this:

Why it’s bad:

• A subquery is used to calculate the sum of ‘total_amount’ for each customer, which can be inefficient. 

Do this instead:

 

 

Use meaningful column aliases:

Don’t do this:

 

Why it’s bad:

• The column alias “x” does not provide any context to the result. 

Do this instead:

 

 

Limit the number of records using the LIMIT clause: 

Don’t do this:

 

Why it’s bad:

• The query returns all records without any limits, which can be inefficient and slow. 

Do this instead:

 

By following these best practices, you can write more efficient and readable SQL queries, making it easier for both you and others to understand and maintain the code.