MAX(): The maximum value in a set of values

SELECT MAX(mark) FROM student

SELECT max( mark ) FROM `student`

SELECT MAX(mark) as max_mark FROM `student` 

Using Subqueries

SELECT id,name,class,MAX(mark) as max_mark FROM `student`

SELECT * FROM `student` WHERE mark=(select max(mark) from student)

Maximum mark in each class by using Group By

SELECT class, max( mark ) as max_mark FROM
`student` GROUP BY class

You can see above that maximum mark of each class is displayed. Since we have two class in our table so the sql command has returned two class with highest mark in each of them. We have to use Group By clause if we ask for the query to return any other field name other than the max. Otherwise system will generate error.

We can add condition to the sql command to get our desired result. We can add one Where clause to the query to consider records for a particular class only  ( say Four)

SELECT max( mark ) as maximu_mark, class FROM student where class ='Four' GROUP BY class

MAX Query with JOIN

SELECT  a.store, MAX(qty) max_qty, b.product,
b.price * MAX(qty) AS total_price  FROM sales a
 LEFT JOIN products b ON a.p_id = b.p_id GROUP BY store;

When integer is stored in VARCHAR field

SELECT MAX ( t1) from max_value

SELECT MAX(CONVERT(t1,UNSIGNED))  FROM `max_value`

CREATE TABLE IF NOT EXISTS `max_value` (
  `t1` varchar(2) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

--
INSERT INTO `max_value` (`t1`) VALUES
('1'),
('2'),
('3'),
('4'),
('5'),
('6'),
('12'),
('13');

Getting Max from a date field

SELECT MAX(exam_dt) FROM student_mark

SELECT MAX(exam_dt) from student_mark group by month(exam_dt)

Storing record with Maximum mark in new table

CREATE TABLE student_max SELECT * FROM `student` WHERE mark=(select max(mark) from student)

INSERT INTO student_max SELECT * FROM `student` WHERE mark=(select max(mark) from student)

Using MAX Query in PHP Script

<?Php
require "config.php";

$count="SELECT class, max( mark ) as max_mark FROM `student` GROUP BY class";

echo "<table>";
echo "<tr><th>class</th><th>max_mark</th></tr>";
foreach ($dbo->query($count) as $row) {
echo "<tr ><td>$row[class]</td><td>$row[max_mark]</td></tr>";
}
echo "</table>";
?>

Understanding the SQL MAX Function in Data Analysis

• Performance Metrics: Analysts use the `MAX` function to gauge peak performance metrics, such as maximum sales in a month or the highest temperature recorded in a region.
• Time Series Analysis: It is crucial for analyzing time-series data, helping to identify the points of maximum activity or interest over a specified period.
• Comparative Analysis: In conjunction with other aggregate functions like `MIN`, `AVG`, and `SUM`, the `MAX` function offers a comprehensive view for comparative analysis across datasets.

• GROUP BY Clause: Used together with the `GROUP BY` clause, `MAX` can reveal the maximum values for each group or category, providing detailed insights into each segment.
• Window Functions: As a window function, `MAX` can assess data over a set of rows related to the current row, enabling complex analytical operations like moving maximum calculations.
• JOIN Operations: When analyzing data from multiple tables, `MAX` can be used in conjunction with JOINs to find maximum values across related datasets.

• Business Intelligence: Identifying the maximum revenue generated by a product to assess its market success.
• Healthcare Analysis: Evaluating the maximum patient wait times to improve healthcare delivery and patient satisfaction.
• Environmental Monitoring: Assessing the maximum pollution levels to identify areas of concern and regulatory compliance.

• Indexing: Proper indexing can enhance query performance, particularly for queries that frequently use the `MAX` function on large datasets.
• Handling of NULL Values: It's important to understand that `MAX` ignores NULL values, which can affect the analysis if not accounted for in data preparation stages.

Conclusion