MySQL - ERREUR 1054 (42S22): Colonne inconnue 'sal' dans 'having clause'

Question

Je dois compter le nombre d'employés par département avec un salaire supérieur à la moyenne.

Mes table employees:

+------+--------+-----------+------+------------+------+------+--------+ 
| eno | ename | job  | mgr | hiredate | sal | comm | deptno | 
+------+--------+-----------+------+------------+------+------+--------+ 
| 7369 | smith | clerk  | 7902 | 1980-12-17 | 800 | NULL |  20 | 
| 7499 | allen | salesman | 7698 | 1981-02-20 | 1600 | 300 |  30 | 
| 7521 | ward | salesman | 7698 | 1981-02-22 | 1250 | 500 |  30 | 
| 7566 | jones | manager | 7839 | 1981-04-02 | 2975 | NULL |  20 | 
| 7654 | martin | salesman | 7698 | 1981-10-28 | 1250 | 1400 |  30 | 
| 7698 | blake | manager | 7839 | 1981-05-01 | 2850 | NULL |  30 | 
| 7782 | clark | manager | 7839 | 1981-06-09 | 2450 | NULL |  10 | 
| 7788 | scott | analyst | 7566 | 1982-12-09 | 3000 | NULL |  20 | 
| 7839 | king | president | NULL | 1981-11-17 | 5000 | NULL |  10 | 
| 7844 | turner | salesman | 7698 | 1981-10-08 | 1500 | NULL |  30 | 
| 7876 | adams | clerk  | 7788 | 1983-01-12 | 1100 | NULL |  20 | 
| 7900 | james | clerk  | 7698 | 1981-12-03 | 950 | NULL |  30 | 
| 7902 | ford | analyst | 7566 | 1981-12-03 | 3000 | NULL |  20 | 
| 7934 | miller | clerk  | 7782 | 1982-01-23 | 1300 | NULL |  10 | 
+------+--------+-----------+------+------------+------+------+--------+ 

La requête que je suis en train de faire est

select deptno, count(*) from emp group by deptno having sal > avg(sal) 

Et c'est quand je reçois l'erreur.

J'ai essayé cette requête aussi:

select deptno, count(*), avg(sal) from emp group by deptno 

Ce qui est fondamentalement le même sauf qu'il n'y a pas de clause ayant, et cela fonctionne comme prévu.

-

select deptno, count(*) from emp where sal > avg(sal) group by deptno

Cette requête jette l'erreur suivante:

ERROR 1111 (HY000): Invalid use of group function

-

select deptno, count(*) from emp group by deptno where sal > avg(sal)

Et cette o n'utilise une syntaxe incorrecte:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'where sal > avg(sal)' at line 1

-

Pourquoi ai-je cette erreur? Quelle serait la bonne façon d'exécuter cette requête? Merci d'avance.

Insertion de script:

SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO"; 
SET time_zone = "+00:00"; 

/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */; 
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */; 
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */; 
/*!40101 SET NAMES utf8 */; 

CREATE TABLE IF NOT EXISTS `emp` (
    `eno` int(11) NOT NULL AUTO_INCREMENT, 
    `ename` varchar(30) DEFAULT NULL, 
    `job` varchar(30) DEFAULT NULL, 
    `mgr` int(11) DEFAULT NULL, 
    `hiredate` date DEFAULT NULL, 
    `sal` int(11) DEFAULT NULL, 
    `comm` int(11) DEFAULT NULL, 
    `deptno` int(11) DEFAULT NULL, 
    PRIMARY KEY (`eno`) 
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=10000 ; 

INSERT INTO `emp` (`eno`, `ename`, `job`, `mgr`, `hiredate`, `sal`, `comm`, `deptno`) VALUES 
(7369, 'smith', 'clerk', 7902, '1980-12-17', 800, NULL, 20), 
(7499, 'allen', 'salesman', 7698, '1981-02-20', 1600, 300, 30), 
(7521, 'ward', 'salesman', 7698, '1981-02-22', 1250, 500, 30), 
(7566, 'jones', 'manager', 7839, '1981-04-02', 2975, NULL, 20), 
(7654, 'martin', 'salesman', 7698, '1981-10-28', 1250, 1400, 30), 
(7698, 'blake', 'manager', 7839, '1981-05-01', 2850, NULL, 30), 
(7782, 'clark', 'manager', 7839, '1981-06-09', 2450, NULL, 10), 
(7788, 'scott', 'analyst', 7566, '1982-12-09', 3000, NULL, 20), 
(7839, 'king', 'president', NULL, '1981-11-17', 5000, NULL, 10), 
(7844, 'turner', 'salesman', 7698, '1981-10-08', 1500, NULL, 30), 
(7876, 'adams', 'clerk', 7788, '1983-01-12', 1100, NULL, 20), 
(7900, 'james', 'clerk', 7698, '1981-12-03', 950, NULL, 30), 
(7902, 'ford', 'analyst', 7566, '1981-12-03', 3000, NULL, 20), 
(7934, 'miller', 'clerk', 7782, '1982-01-23', 1300, NULL, 10); 

/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */; 
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */; 
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */; 

Answer 1

Essayez de rejoindre l'ensemble avec la table

select emp.depnto, count(*) from 
(select deptno, avg(sal) avgsal from employees group by deptno) avg 
INNER JOIN employees emp on avg.deptno = avg.depnto 
WHERE emp.sal > avg.avgsal 

EDIT

Peut-être que je thoght à compliqué. Lorsque la moyenne globale est signifiée, il est simplement

select depnto, count(*) from employees 
where sal > (select avg(sal) from employees) 
group by deptno 

Answer 2

Vous avez la virgule avant de

select deptno, count(*) 
from emp 
group by deptno having sal > (select avg(sal)from emp); 

Answer 3

Il n'y a pas besoin d'utiliser HAVING. Essayez OÙ à la place:

select deptno, count(*) from emp WHERE sal > avg(sal) group by deptno 

Answer 4

Essayez cette

SELECT deptno as Department , count(eno) as employeeCount from emp 
where sal > (select avg(sal) from emp) group by deptno