Reputation: 82
I'm trying to find all employees with multiple skills. Here are the tables:
CREATE TABLE IF NOT EXISTS `Employee` (
`ID` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`Name` varchar(100) DEFAULT NULL,
PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3 ;
INSERT INTO `Employee` (`ID`, `Name`, `Region_ID`) VALUES (1, 'Fred Flintstone'), (2, 'Barney Rubble');
CREATE TABLE IF NOT EXISTS `Skill` (
`ID` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`Name` varchar(100) DEFAULT NULL,
PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3 ;
INSERT INTO `Skill` (`ID`, `Name`) VALUES (1, 'PHP'), (2, 'JQuery');
CREATE TABLE IF NOT EXISTS `Emp_Skills` (
`ID` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`Emp_ID` bigint(20) unsigned NOT NULL DEFAULT '0',
`Skill_ID` bigint(20) unsigned NOT NULL DEFAULT '0',
PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=5 ;
INSERT INTO `Emp_Skills` (`ID`, `Emp_ID`, `Skill_ID`) VALUES (1, 1, 1), (2, 1, 2), (3, 2, 1);
Here is the query I have so far:
SELECT DISTINCT(em.ID), em.Name
FROM Employee em
INNER JOIN Emp_Skills es ON es.Emp_ID = em.ID
WHERE es.Skill_ID IN ('1', '2')
This returns both employees, however, I need to find the employee that has both skills (ID 1 and 2).
Any ideas? Thanks
Upvotes: 5
Views: 2457
Reputation: 1271241
You can do this with aggregation and a having
clause:
SELECT em.ID, em.Name
FROM Employee em INNER JOIN
Emp_Skills es
ON es.Emp_ID = em.ID
GROUP BY em.id, em.name
HAVING sum(es.Skill_id = '1') > 0 and
sum(es.Skill_id = '2') > 0;
Each condition in the having
clause counts the number of rows for each employee that have a particular skill. The filter guarantees that both skills are present.
Upvotes: 3
Reputation: 107407
This will do it:
SELECT EmpId, Name
FROM
(
SELECT em.ID as EmpId, em.Name, es.ID as SkillID
FROM Employee em
INNER JOIN Emp_Skills es ON es.Emp_ID = em.ID
WHERE es.Skill_ID IN ('1', '2')
) X
GROUP BY EmpID, Name
HAVING COUNT(DISTINCT SkillID) = 2;
The distinct is just in case the same employee has the skill listed twice.
Thanks for the test data.
Upvotes: 4