Hackerrank Pattern Questions — SQL

Problem:

P(R) represents a pattern drawn by Julia in R rows. The following pattern represents P(5):

* 
* * 
* * * 
* * * * 
* * * * *

Write a query to print the pattern P(20).

Solution :

DELIMITER $$

CREATE PROCEDURE stars(r INT) -- procedure stars() with r as an int
BEGIN
    DECLARE star INT DEFAULT 1; -- declare star as a variable
    WHILE star <= r DO -- loop as long as star is <= r
        SELECT REPEAT('* ', star); -- print out * star number of times
        SET star = star + 1; -- increment +1 for each counted row        
    END WHILE;
END $$
    
CALL stars(20); -- call procedure with the value 20

1. You’ll need to use two sets of variables (one input for the rows and another to count all of the rows), in my answer I used “r int” and “star int”.
2. Make sure that your logic is “star <= r” as you want WHILE loop to only last as long as the value of r (which is your procedure input).

Output:

*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
* * * * * * * *
* * * * * * * * *
* * * * * * * * * *
* * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * * *
* * * * * * * * * * * * * *
* * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * *

Happy coding!

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