MYSQL检查是否所有表1条目都有表2条目

我有两张员工表和证书。现在我有4个证书，我想检查每个员工哪些证书通过了，哪些没有通过

Select Distinct(certificate.certificatename)
FROM `employeemanagement$certificate` certificate
Where certificatename = '**********' 
or certificatename = '************'
or certificatename = '************'
or certificatename = '************'

这将给我4个我想要的证书

SELECT employees.employeeid, employees.employeename, certificate.certificatename, certificate.expirationdate, certificate.`status`
FROM `employeemanagement$employees` employees 
LEFT JOIN `employeemanagement$certificate_employees` certifcate_employees on employees.id = certifcate_employees.`employeemanagement$employeesid`
LEFT JOIN `employeemanagement$certificate` certificate on certificate.id = certifcate_employees.`employeemanagement$certificateid`
Where employees.currentstatus = 'Active'

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这会给我所有员工的所有证书，但不会给我每个证书的结果

我认为条件聚合是一种合理的方法：

SELECT e.employeeid, e.employeename, 
       MAX(CASE WHEN c.certificatename = 'C1' THEN  c.expirationdate END) as c1_expiration,
       MAX(CASE WHEN c.certificatename = 'C1' THEN  c.staus END) as c1_status, 
       MAX(CASE WHEN c.certificatename = 'C2' THEN  c.expirationdate END) as c2_expiration,
       MAX(CASE WHEN c.certificatename = 'C2' THEN  c.staus END) as c2_status, 
       MAX(CASE WHEN c.certificatename = 'C3' THEN  c.expirationdate END) as c3_expiration,
       MAX(CASE WHEN c.certificatename = 'C3' THEN  c.staus END) as c3_status, 
       MAX(CASE WHEN c.certificatename = 'C4' THEN  c.expirationdate END) as c4_expiration,
       MAX(CASE WHEN c.certificatename = 'C4' THEN  c.staus END) as c4_status
FROM `employeemanagement$employees` e LEFT JOIN 
     `employeemanagement$certificate_employees` ce
      ON e.id = ce.`employeemanagement$employeesid` LEFT JOIN
     `employeemanagement$certificate` c
     ON c.id = ce.`employeemanagement$certificateid`
WHERE e.currentstatus = 'Active'
GROUP BY e.employeeid;

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您可能会发现，将所有证书汇总到每名员工的一行，而不是每名证书的多行，这样做会更轻松。

删除

Where employees.currentstatus='Active'

并运行查询时会发生什么？然后它将显示所有员工。这没关系，因为我只需要在职员工的记录