Comments are used to add information to the code. It is mostly ignored by the compiler, but human specialists can read those comments when they view your code. Comments are essential for developers because they have limited time, and commenting allows them to get valuable information at once or note some crucial details in regards to the code. Accessing this data lets them make the right decisions and work faster.Read More
Typical queries in the SELECT * FROM table format are sometimes not enough. When the data for a query is not in one table, but in several, or when it is necessary to specify several selection parameters at once, you will need more sophisticated queries.
This article will explain how to build such queries and provide examples of complex SQL queries.Read More
Hash indexes are an integral part of databases. If you’ve ever used a database, chances are that you have seen them in action without even realizing it.
Hash indexes differ in work from other types of indexes because they store values rather than pointers to records located on a disk. This ensures faster searching and insertion into the index. That’s why hash indexes are often used as primary keys or unique identifiers.Read More
Cartesian product in SQL is a term from the set theory of mathematics. However, we can also find this term in SQL database manuals. What does it mean, and how should we work with it? Let’s learn it.
A Cartesian product of two sets X and Y, denoted X × Y, is the set of all ordered pairs where x is in X and y is in Y.Read More