I have been trying to learn SQL and BI. I used to think that those are unnecessary since I can do everything via Python (querrying, pivoting, group by and visualisation). But within 2 days of learning them, I can see why they are useful.

SQL

SQL is relatively easy to learn for me (at least up to intermediate and some advance). Soon enough I realise I can only get better via practise. I cannot just simply watch tutorial. I learnt the basic via YouTube, then practise, practise and practise to get used to SQL.

Some recommendations for future learners:

• This youtube tutorial gave a good basic foundation for SQL
• This web provides a lot of practise question
• Second web that provides SQL explanation and also provided examples of SQL problem typically encountered on the job
• Free account from this web provides interview style exercies for SQL

I am lucky enough to have an access to a real database from my family’s restaurant business. So I used Microsoft SQL Server Management Studio to access the database and try to extract relevant sales and customer information. My first reaction was there are so many tables in our database (could be the inefficiency of our programmer, but I am not sure). It took me a while to find the info that I might be interested. Quick google search easily tell me querries to list tables that are not empty. I started from there until I find out how to download the right information. The next step was then using the data that I extracted for BI visualisation.

BI

BI software definitely can provide access to visualise data without knowing any programming. I can see why they are useful for analysts, managers and others.

As with many, I started learning the two most common BI software: Tableau and Power BI. Of course via YouTube as usual. Then I used the database from our restaurant business with each platform.

My first opinion was I prefer Tableau than Power BI. Tableau was more intuitive. However, looking at the subscription pricing, I quickly realised that this may not be feasible for us since we are a small business. I then focus my effort on Power BI, visualising sales per category, top 10 food and drinks, average sales for dine-in vs take-away and customer density visiting our restaurant.

One random thing I learnt was how much take away boxes that we sold! This may indicate that our food have a large portion and we should look to reduce it.