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목록HackerRank/SQL (7)
조컴퓨터
hackerrank Draw The Triangle 2
1) SET 1-1) SET @row := 0; 2) * 반복 2-1) REPEAT( "* ", @row := @row + 1 ) 3) INFORMATION_SCHEMA.tables 3-1) SET @row :=0; SELECT REPEAT("* ", @row := @row + 1 ) FROM INFORMATION_SCHEMA.tables 4) where절 4-1) SET @row := 0; SELECT REPEAT("* ", @row := @row + 1 ) FROM INFORMATION_SCHEMA.tables WHERE @row < 20; 4-1) 결과 이하 20줄까지 출력된다. SUCCESS!!
hackerrank Weather Observation Station 6
1) 정규표현식 1-1) SELECT city FROM STATION WHERE city REGEXP '^[aeiou]'; 1-1) 결과 mysql 정규표현식 regexp 1) 문자열에 '한글'이 표함된 경우 1-1) SELECT * FROM 테이블명 WHERE name REGEXP '[가-힣]'; 2) 문자열의 시작이 '한글'인 경우 2-1) SELECT * FROM 테이블명 WHERE name REGEXP '^[가-힣]'; 3) 문자열의 끝이 '한글'인 경우 3-1) SELECT * FROM 테이블명 WHERE name REGEXP '[가-힣]$'; 4) 모든 문자열이 '한글'인 경우 4-1) SELECT * FROM 테이블명 WHERE name REGEXP '^[가-힣]+$'; 5) 문자열에 '영어..
hackerrank Weather Observation Station 5
1) 짧은 도시명 1-1) SELECT city, LENGTH(city) FROM STATION ORDER BY LENGTH(city), city; 1-1) 결과 1-2) SELECT * FROM ( SELECT city, LENGTH(city) FROM STATION ORDER BY LENGTH(city), city ) WHERE rownum = 1; 1-2) 결과 2) 가장 긴 도시명 2-1) SELECT city, LENGTH(city) FROM STATION ORDER BY LENGTH(city) DESC, city DESC; 2-1) 결과 2-2) SELECT * FROM ( SELECT city, LENGTH(city) FROM STATION ORDER BY LENGTH(city) DESC, ..
hackerrank Weather Observation Station 3
1) MOD(id, 2) = 0 1-1) SELECT city FROM STATION WHERE MOD(id, 2) = 0; 1-1) 결과 2) 중복 체크 2-1) SELECT city FROM STATION WHERE MOD(id, 2) = 0 GROUP BY city; 2-1) 결과 SUCCESS!!
hackerrank Symmetric Pairs
1) X = Y 1-1) SELECT X, Y FROM Functions WHERE X = Y GROUP BY X, Y 1-1) 결과 1-2) COUNT(*) SELECT X, Y, COUNT(*) FROM Functions WHERE X = Y GROUP BY X, Y HAVING COUNT(*) = 2 1-2) 결과 2) X1 = Y1 AND X2 = Y2 2-1) SELECT f1.X, f1.Y FROM Functions f1, Functions f2 WHERE f1.X = f2.Y AND f2.X = f1.Y AND f1.X < f1.Y -- f1.X f1.Y / 단, 이 경우에는 중첩되므로 f1.X < f1.Y 인 한 가지 경우만 사용 2-1) 결과 3) UNION 3-1) SELECT X, Y..
hackerrank Type of Triangle
1) 정사각형 A=B AND B=C 1-1) SELECT CASE WHEN A=B AND B=C THEN 'Equilateral' ELSE '그외' END, A, B, C FROM TRIANGLES 2) 이등변 삼각형 2-1) SELECT CASE WHEN A=B AND B=C THEN 'Equilateral' WHEN A=B OR A=C OR B=C THEN 'Isosceles' ELSE '그외' END, A, B, C FROM TRIANGLES 2-2) SELECT CASE WHEN A=B AND B=C THEN 'Equilateral' WHEN A=B AND A+B>C OR A=C AND A+C>B OR B=C AND B+C>A THEN 'Isosceles' ELSE '그외' END, A, B, C..
hackerrank Top Earners
1) salary * months = earnings 1-1) SELECT *, salary * months AS earnings FROM Employee 1-2) SELECT salary * months AS earnings FROM Employee GROUP BY earnings 1-3) SELECT salary * months AS earnings FROM Employee GROUP BY earnings ORDER BY earnings 1-4) SELECT salary * months AS earnings FROM Employee GROUP BY earnings ORDER BY earnings DESC 1-5) SELECT salary * months AS earnings FROM Employee ..