1: Statement order of grouping function1 SELECT ... 2 FROM ... 3 WHERE ... 4 GROUP BY ... 5 HAVING ... 6 ORDER BY ... 2. The difference between WHERE and HAVING filter conditionsData source location keyword WHERE Original table ORDER BY statement before WHERE HAVING Grouped result set after ORDER BY statement HAVING Three: Examples#1. Query the maximum age of students in each classSELECT MAX(age),class FROM STU_CLASS GROUP BY CLASS; # 2. Query the maximum age of male and female students in each class SELECT MAX(age), class, sex FROM STU_CLASS GROUP BY class,sex; #3. Query the average age of boys and girls in each class, and the average age is greater than 15 years old SELECT AVG (age), class, sex FROM STU_CLASS GROUP BY class,sex HAVING avg(age) > 15; Four: Note1. Usually, the GROUP BY keyword is used together with an aggregate function. First, the GROUP BY keyword is used to group the records, and then the aggregate function is used to calculate each group. The GROUP BY keyword and aggregate functions are often needed when performing statistics. The above is the detailed content of the detailed explanation of the group by statement of MySQL database group query. For more information about MySQL database statements, please pay attention to other related articles on 123WORDPRESS.COM! You may also be interested in:
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