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SQL - Recursion

SQL - Recursion

Introduction Recursion in SQL is a lesser known technique, this technique is just like we expect as it would work in any developing language such as C, Javascript, …, it allows us to create a query that will be able to recursively get and process data to find a result. Think

SQL - Part 5 - Common Table Expressions

SQL - Part 5 - Common Table Expressions

CTE's (Common Table Expressions) are mostly used when creating recursive queries, creating temporary views (instead of subqueries). Calculating the dates of easter Use case And Example: We want to calculate the dates of when it is easter for the next hundred years. Solution:Since we are explaining examples

SQL - Part 4 - JOIN + Simulating Functions

SQL - Part 4 - JOIN + Simulating Functions

When creating JOIN queries in SQL we have to realize that we are going to combine every result from the result set with the result set itself. This means that we are going to create a new result set that is the size of the power of 2 of our

SQL - Part 3 - Analytical Functions (Ranking, Rows, Over, ...)

SQL - Part 3 - Analytical Functions (Ranking, Rows, Over, ...)

Analytical Functions Analytical functions are brought into existence to solve the problems that we have with Aggregate functions. The biggest disadvantage of these Aggregate functions is that they always reduce the number of results, but what if we want to be able to perform functions on all our results based

SQL - Part 2 - Aggregate Functions (GROUP BY, CUBE, ROLLUP, ...)

SQL - Part 2 - Aggregate Functions (GROUP BY, CUBE, ROLLUP, ...)

Aggregate Functions Aggregate functions are functions that are going to aggregate data from columns, or rows. Some of these functions are: SUM, AVG, MAX, MIN, …. . Special GROUP BY where we are going to group by values using a CASE and then sort by based on that case Example: In this

SQL - Part 1 - Advanced CASE Selecting

SQL - Part 1 - Advanced CASE Selecting

While I was studying the course Databases at the University of Ghent, we encountered some special queries that we were not being thaught in the Professional Bachelor course. This is why I tried to summarise those queries here for everyone to learn from. The database engine being used is Oracle

Solving a maze with Perl

Solving a maze with Perl

Mazes are really famous puzzles where the goal is to find the exit starting from an entrance. We can see these kind of puzzles as a labyrinth. When we found the solution we then draw over them to mark the path that we have to find. Most of the time