mySQL 显示具有多次出现的公共属性的行
mySQL showing rows that have multiple occurences of common attributes
我在以特定方式显示数据时遇到了一些问题。
我想显示3个或更多技能共有的机制
我不确定如何计算常用技能,我尝试使用 EXIST 和子查询但无法弄清楚。
这是我必须显示所有具有他们技能的机械师的查询
Select distinct fName, lName , Skill from Person
inner join Worker on Person.personID = Worker.personID
inner join Mechanic on Worker.personID = Mechanic.personID
inner join Skills on Mechanic.personID = Skills.personID
order by fName
显示
fName lName Skill
----------------------------
Carl Marx fuel systems
Jimmy John heating and cooling systems
Jimmy John exhaust systems
Jimmy John fluid and filter service
Mike Hawk resurface rotors and drums
Mike Hawk struts and suspension
Mike Hawk engine performance (tune-up)
Mike Hawk wheel alignment
Ricky Bobby wheel alignment
Ricky Bobby resurface rotors and drums
Ricky Bobby A/C systems
Ricky Bobby struts and suspension
Ricky Bobby heating and cooling systems
Terry Cruz sound systems
Terry Cruz cruise control
输出应该是
Ricky Bobby
Mike Hawk
这是关系图
提前致谢!让我知道我是否可以提供其他任何东西
select fname,lname from Person where skills >= 3 order by fname
SELECT `fNameA`, `lNameA`, `fNameB`, `lNameB`, GROUP_CONCAT(`SkillA`, ' ') as Skills
FROM (
SELECT DISTINCT
CASE WHEN M1.`id` < M2.`id` THEN M1.`fName` ELSE M2.`fName` END as `fNameA`,
CASE WHEN M1.`id` < M2.`id` THEN M1.`lName` ELSE M2.`lName` END as `lNameA`,
CASE WHEN M1.`id` < M2.`id` THEN M2.`fName` ELSE M1.`fName` END as `fNameB`,
CASE WHEN M1.`id` < M2.`id` THEN M2.`fName` ELSE M1.`fName` END as `lNameB`,
M1.`Skill` as `SkillA`, M2.`Skill` as `SkillB`
FROM Mechanic M1
JOIN Mechanic M2
ON M1.`id` <> M2.`id`
AND M1.`Skill` = M2.`Skill`
ORDER BY M1.`id`, M2.`id`) T
GROUP BY `fNameA`, `lNameA`, `fNameB`, `lNameB`
HAVING COUNT(*) >= 3;
简单版 只打印前两个字段
SELECT M1.`fName`, M1.`lName`, M2.`fName`, M2.`lName`
FROM Mechanic M1
JOIN Mechanic M2
ON M1.`id` <> M2.`id`
AND M1.`Skill` = M2.`Skill`
GROUP BY M1.`fName`, M1.`lName`, M2.`fName`, M2.`lName`
HAVING COUNT(*) >= 3;
输出
- 部分结果
- 第一个版本有技能列表
- 简单版
我在以特定方式显示数据时遇到了一些问题。
我想显示3个或更多技能共有的机制
我不确定如何计算常用技能,我尝试使用 EXIST 和子查询但无法弄清楚。
这是我必须显示所有具有他们技能的机械师的查询
Select distinct fName, lName , Skill from Person
inner join Worker on Person.personID = Worker.personID
inner join Mechanic on Worker.personID = Mechanic.personID
inner join Skills on Mechanic.personID = Skills.personID
order by fName
显示
fName lName Skill
----------------------------
Carl Marx fuel systems
Jimmy John heating and cooling systems
Jimmy John exhaust systems
Jimmy John fluid and filter service
Mike Hawk resurface rotors and drums
Mike Hawk struts and suspension
Mike Hawk engine performance (tune-up)
Mike Hawk wheel alignment
Ricky Bobby wheel alignment
Ricky Bobby resurface rotors and drums
Ricky Bobby A/C systems
Ricky Bobby struts and suspension
Ricky Bobby heating and cooling systems
Terry Cruz sound systems
Terry Cruz cruise control
输出应该是
Ricky Bobby
Mike Hawk
这是关系图
提前致谢!让我知道我是否可以提供其他任何东西
select fname,lname from Person where skills >= 3 order by fname
SELECT `fNameA`, `lNameA`, `fNameB`, `lNameB`, GROUP_CONCAT(`SkillA`, ' ') as Skills
FROM (
SELECT DISTINCT
CASE WHEN M1.`id` < M2.`id` THEN M1.`fName` ELSE M2.`fName` END as `fNameA`,
CASE WHEN M1.`id` < M2.`id` THEN M1.`lName` ELSE M2.`lName` END as `lNameA`,
CASE WHEN M1.`id` < M2.`id` THEN M2.`fName` ELSE M1.`fName` END as `fNameB`,
CASE WHEN M1.`id` < M2.`id` THEN M2.`fName` ELSE M1.`fName` END as `lNameB`,
M1.`Skill` as `SkillA`, M2.`Skill` as `SkillB`
FROM Mechanic M1
JOIN Mechanic M2
ON M1.`id` <> M2.`id`
AND M1.`Skill` = M2.`Skill`
ORDER BY M1.`id`, M2.`id`) T
GROUP BY `fNameA`, `lNameA`, `fNameB`, `lNameB`
HAVING COUNT(*) >= 3;
简单版 只打印前两个字段
SELECT M1.`fName`, M1.`lName`, M2.`fName`, M2.`lName`
FROM Mechanic M1
JOIN Mechanic M2
ON M1.`id` <> M2.`id`
AND M1.`Skill` = M2.`Skill`
GROUP BY M1.`fName`, M1.`lName`, M2.`fName`, M2.`lName`
HAVING COUNT(*) >= 3;
输出
- 部分结果
- 第一个版本有技能列表
- 简单版