Unveiling the Power of Data Summarization — In the previous two parts, you’ve learned how to select data from single and multiple tables. You know how to filter rows and join columns from different tables. In this part, you’ll learn how to compute statistics, group rows, and filter such groups. KNOW THE TABLE Naturally, one employee can work for more…

Learn how to select data from multiple tables Single tables might seem handy at first, but we always use multiple tables in big databases. This also means that we often want to get data from more than one table at a time. …

It's time to push yourself and aim for progress once again! — See the whole table 7. Get all data It’s time to run your first SQL query! As you remember, the data in a database are stored in tables. You can see all data in the user table with this query: SELECT * FROM user; SELECT tells your database that you want to select data. …

Contents: What is a database exactly? Tables Columns & Rows Notation SQL Queries 1. What is a database exactly? To put it simply, it’s a computer program which stores various data. There are quite a few database vendors e.g., Oracle, MySQL, PostgreSQL, SQL Server, and many others. …