In this tutorial, we will learn how to use different mathematical functions in order to interpret data better, and how to create reports.
Clean data using SQL mathematical functions (ABS, SIGN, MOD, etc.).
Learn how to write comments in SQL
Creating reports by applying aggregation methods.
We're going to let you in on a secret. SQL can perform most mathematical functions for you independent of the schema. Often when writing queries you may need to do some quick calculations. You can save time by performing the calculations in SQL itself.
In the previous article we learned how to write simple SQL queries. Now, we will expand our skillset to learn how to aggregate data using aggregation commands.
Write Boolean statements with the IN SQL conditional operator and null functions (IS NULL, IFNULL, IS NOT NULL, and <>).
Summarize data sets by employing aggregation functions (Sum, Average, Count, etc.).
Let's say that you have recently started working for a restaurant supply wholesaler. You are tasked with leveraging the sales inquiry table to manage client communication more efficiently. Additionally, you have to co-ordinate with the sales people to ensure all queries are answered. Let’s look at some examples.
While there are many definitions of good design, and many opinions on what good design means, the "10 Principles of Good Design" by Dieter Rams is generally the most universally agreed upon set of rules that can serve as a good definition of good design. Here they are: