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Julia conducted a 15 days of learning SQL contest. The start date of the contest was March 01, 2016 and the end date was March 15, 2016. Write a query to print total number of unique hackers who made at least 1 submission each day (starting on the first day of the contest), and find the hacker_id and name of the hacker who made maximum number of submissions each day. If more than one such hacker..

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). DELIMITER $$ CREATE PROCEDURE PrintStar2(IN NUM INT) BEGIN SET @I = 1; WHILE (@I

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). MS-SQL에서는 무지 쉽다. DECLARE @NUM INT = 20 WHILE @NUM > 0 BEGIN SELECT REPLICATE('* ',@NUM) SET @NUM = @NUM - 1 END MYSQL은 뭔지 몰라서 한참 찾았다. LPAD 또는 RPAD를 사용하면 되는데 중요한 것은 2번째 인자이다. REPLICATE는 특별하게 생각할 필요없이 반복한 숫자를 넣어주면 되지만 LPAD/RPAD는 최종 문자열의 길이를 정해줘야 한다. 즉, '*'만 찍어야 하는 것이..

You are given a table, Functions, containing two columns: X and Y. Two pairs (X1, Y1) and (X2, Y2) are said to be symmetric pairs if X1 = Y2 and X2 = Y1. Write a query to output all such symmetric pairs in ascending order by the value of X. List the rows such that X1 ≤ Y1. Sample Input Sample Output 20 20 20 21 22 23 SELECT F1.X, F1.Y FROM Functions F1 JOIN Functions F2 ON (F1.X = F2.Y AND F1.Y ..