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SQL Challenges-1: Highest Single marks

SQL Challenges-1: Exercise-23 with Solution

Table students contain marks of mathematics for several students in a class. It may same marks for more than one student.
From the following table write a SQL table to find the highest unique marks a student achieved. Return the marks.

Input:

Table: students

Structure:

FieldTypeNullKeyDefaultExtra
student_idint(11)YES
student_namevarchar(255)YES
marks_achievedint(11)YES

Data:

student_idstudent_namemarks_achieved
1Alex87
2Jhon92
3Pain83
4Danny87
5Paul92
6Rex89
7Philip87
8Josh83
9Evan92
10Larry87

Sample Solution:

SQL Code(MySQL):

CREATE TABLE students(student_id int, student_name varchar(255), marks_achieved int);

INSERT INTO students VALUES(1, 'Alex',87);
INSERT INTO students VALUES(2, 'Jhon',92);
INSERT INTO students VALUES(3, 'Pain',83);
INSERT INTO students VALUES(4, 'Danny',87);
INSERT INTO students VALUES(5, 'Paul',92);
INSERT INTO students VALUES(6, 'Rex',89);
INSERT INTO students VALUES(7, 'Philip',87);
INSERT INTO students VALUES(8, 'Josh',83);
INSERT INTO students VALUES(9, 'Evan',92);
INSERT INTO students VALUES(10, 'Larry',87);

SELECT * FROM students;
 
SELECT MAX(marks_achieved) as marks
FROM (
	SELECT marks_achieved
	FROM students
	GROUP BY marks_achieved
	HAVING COUNT(*) = 1
) z;

Sample Output:

marks|
-----|
   89|

SQL Code Editor:


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SQL: Tips of the Day

How to select the nth row in a SQL database table?

Basically, PostgreSQL and MySQL supports the non-standard:

SELECT...
LIMIT y OFFSET x 

Oracle, DB2 and MSSQL supports the standard windowing functions:

SELECT * FROM (
  SELECT
    ROW_NUMBER() OVER (ORDER BY key ASC) AS rownumber,
    columns
  FROM tablename
) AS foo
WHERE rownumber <= n

Database: SQL

Ref: https://bit.ly/3zPxcD8