Summary Functions in mysql

Summary Functions

SELECT Dept, Level, ROUND(AVG(TotalStudents)) AS Average
FROM Classes
GROUP BY Dept, Level WITH ROLLUP;

use of the WITH ROLLUP option in the GROUP BY clause. As a result, averages are provided for the departments as a whole and for all classes added together.

SELECT Dept, Level, SUM(TotalStudents) AS Total
FROM Classes
GROUP BY Dept, Level WITH ROLLUP
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SELECT Dept, Level, MIN(TotalStudents) AS Minimum
FROM Classes
GROUP BY Dept, Level WITH ROLLUP;
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SELECT Dept, Level, MAX(TotalStudents) AS Maximum
FROM Classes
GROUP BY Dept, Level WITH ROLLUP;

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SELECT Dept, Level, COUNT(*) AS NumberClasses
FROM Classes
GROUP BY Dept, Level WITH ROLLUP;