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kurs:joins [2014/09/10 21:22] 127.0.0.1 external edit |
kurs:joins [2020/05/12 10:09] (current) admin |
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+ | </code> | ||
+ | |||
+ | Join über mehrere Tabellen hinweg | ||
+ | <code> | ||
+ | SELECT | ||
+ | first_name, | ||
+ | last_name, | ||
+ | coalesce(department_name, '[kein department]'), | ||
+ | city, | ||
+ | country_name, | ||
+ | region_name | ||
+ | FROM | ||
+ | hr.employees | ||
+ | left JOIN hr.departments ON employees.department_id = departments.department_id | ||
+ | left join hr.locations on departments.location_id = locations.location_id | ||
+ | left join hr.countries on locations.country_id = countries.country_id | ||
+ | left join hr.regions on countries.region_id = regions.region_id | ||
+ | where region_name = 'Europe' | ||
+ | </code> | ||
+ | |||
+ | <code> | ||
+ | SELECT | ||
+ | first_name, | ||
+ | last_name, | ||
+ | e.department_id aktuelle_department_id, | ||
+ | jh.department_id jh_department_id, | ||
+ | e.job_id aktuelle_job_id, | ||
+ | jh.job_id jh_job_id, | ||
+ | start_date, | ||
+ | end_date | ||
+ | FROM | ||
+ | employees e left JOIN job_history jh | ||
+ | ON e.employee_id = jh.employee_id | ||
+ | ORDER BY | ||
+ | coalesce(e.employee_id, jh.employee_id) | ||
</code> | </code> |