将几行转置为列的 SQL 查询

如何解决将几行转置为列的 SQL 查询

工作表

 Job id 
 Job title
 job type

JobID  jobTitle  jobType
1       design    manual
2       test      automated
3       deploy    automated

jobEmp 表

 emp id
 job id
 first name
 last name
 job role(manager,lead,dev)

empid  jobid  firstname  lastname  jobrole
1       1       mickey    mouse      1
2       1       minnie    mouse      2
3       1       tom        jerry     3
4       2       minnie    mouse      1
5       2       abc                  3

因此一个作业可以有超过 1 个 emp，因此 jobEmp 表中单个作业将有超过 1 行。

我需要使用以下输出编写查询

jobId | jobTitle | jobType | manager      |   Lead       | dev
 1       Design     manual   mickey mouse   minnie mouse   tom jerry
 2       Test    Automated   minnie mouse   abc

请帮忙！

解决方法

您可以通过以下方式进行：

SELECT DISTINCT (*) FROM
(SELECT
j.jobId,j.jobTitle,j.jobType,CONCAT (je.first_name,je.last_name) AS NAME
FROM job j
INNER JOIN jobEmp as je) as JobTable

JOIN (SELECT DISTINCT jobRole AS 'manager' 
FROM jobEmp
WHERE 
role = 'manager'
 ) AS manager_col
 ON manager_col.jobId = JobTable.jobId 

JOIN (SELECT DISTINCT jobRole AS 'Lead' 
FROM jobEmp
WHERE 
role = 'lead'
 ) AS lead_col
 ON lead_col.jobId = JobTable.jobId 

JOIN (SELECT DISTINCT jobRole AS 'dev' 
FROM jobEmp
WHERE 
role = 'dev'
 ) AS dev_col

 ON dev.jobId = JobTable.jobId 

请确保根据您的表格名称进行更改，因为我猜例如 Job id 之间没有空格