SQL Tutorial: Introduction to recursion

Key Takeaways

in the second video you will learn what you cash means and how you could use it for many problems the first question we want to answer is what recursion is in general as you can see in the picture it is something that is always repeated accordingly recursion is the use of a procedure subroutine function or eggwin that calls itself one or more times until a specific condition is met therefore a recursion could simplify a complex problem by sharing the problem in smaller poems performed repeatedly one really important fact about recursion is that you need the termination condition if you have no termination condition the call of the small problem repeats all the time as you can see in the shown picture and we world example everyone knows it's the family tree everyone has a father and your father as a father for example to find all father's for the last five generations you can use your question you have to reduce the problem to smaller problems of the same type whole problem is to find all generations and the small problem is to find your father in the first step find your father and in the second step find the father of the father until the termination condition of fife is reached knowing how we crashed works in Genoa we are now somewhere some facts about recursion advantages soft bottoms recursively if the bottom can be reduced to smaller partners of the same type and recursively solve problem is easy to eat and to follow and the termination condition could be used to limit the number of iterations thinking of disadvantages the Oshin time could be slower because the recursion function is called many times knowing what is recursion let's try out a simple macaron problem the problem we want to solve is to calculate the sum of consecutive numbers it can be defined as shown on the slide it is 1 for the first situation and for each following iteration number of the current iteration and the sum of the previous situation is added as an example the result of 5 is 15 is this the sum of 1 plus 2 Plus 3 plus 4 plus 5 now we are going to solve this problem with seeker in general we could solve recursive problems with city's common table expressions therefore you could see the initial query which initializes the field for iteration and the sum of number with one in the recursive part the current iteration number is added with the sum of the previous situation you can see that the termination condition is set to 6 this means this query calculates the sum of numbers until 6 finally the city is elected to get the wanted result you hear a lot about who curses afar