SQL MAX function is used to find out the record with the maximum value among a record set.
To understand MAX function, consider an employee_tbl table, which is having the following records −
SQL> SELECT * FROM employee_tbl;
+------+------+------------+--------------------+
| id | name | work_date | daily_typing_pages |
+------+------+------------+--------------------+
| 1 | John | 2007-01-24 | 250 |
| 2 | Ram | 2007-05-27 | 220 |
| 3 | Jack | 2007-05-06 | 170 |
| 3 | Jack | 2007-04-06 | 100 |
| 4 | Jill | 2007-04-06 | 220 |
| 5 | Zara | 2007-06-06 | 300 |
| 5 | Zara | 2007-02-06 | 350 |
+------+------+------------+--------------------+
7 rows in set (0.00 sec)
Now suppose based on the above table you want to fetch the maximum value of daily_typing_pages, then you can do so simply using the following command −
SQL> SELECT MAX(daily_typing_pages)
-> FROM employee_tbl;
+-------------------------+
| MAX(daily_typing_pages) |
+-------------------------+
| 350 |
+-------------------------+
1 row in set (0.00 sec)
You can find all the records with maximum value for each name using the GROUP BY clause as follows −
SQL> SELECT id, name, MAX(daily_typing_pages)
-> FROM employee_tbl GROUP BY name;
+------+------+-------------------------+
| id | name | MAX(daily_typing_pages) |
+------+------+-------------------------+
| 3 | Jack | 170 |
| 4 | Jill | 220 |
| 1 | John | 250 |
| 2 | Ram | 220 |
| 5 | Zara | 350 |
+------+------+-------------------------+
5 rows in set (0.00 sec)
You can use MIN Function along with the MAX function to find out the minimum value as well. Try out the following example −
SQL> SELECT MIN(daily_typing_pages) least, MAX(daily_typing_pages) max
-> FROM employee_tbl;
+-------+------+
| least | max |
+-------+------+
| 100 | 350 |
+-------+------+
1 row in set (0.01 sec)
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