MySQL:选择联接表匹配所有值的记录 [英] MySQL: Select records where joined table matches ALL values

问题描述

我正在寻找所有具有多种技能的员工.这是表格:

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);

这是我到目前为止的查询:

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')

这将返回两名雇员，但是，我需要找到具有两种技能(ID 1和2)的雇员.

This returns both employees, however, I need to find the employee that has both skills (ID 1 and 2).

有什么想法吗?谢谢

推荐答案

这可以做到:

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;

在此处进行提示:

不同之处在于，如果同一位员工具有两次列出的技能.

The distinct is just in case the same employee has the skill listed twice.

感谢测试数据.

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