使用联接SQL Oracle更新表

Question

I need to update several columns of a table, but one piece of information is stored in another table, so I'm assuming I need to join them but I'm unsure how to. Basically I need to update the job title where the office is T06 and the start date where the original start_date was '05-FEB-09, 08:00' for the staff whose last name is Parker

So far I have:

UPDATE JOB
SET JOB_TITLE = 'Head of Technology'
WHERE OFFICE = 'T06' 
AND SET START_DATE = '26-JUN-17, 08:00'
WHERE START_DATE = '05-FEB-09, 08:00'
FROM JOB
JOIN STAFF
ON JOB.STAFF_ID = STAFF.STAFF_ID
WHERE STAFF.LAST_NAME = 'Parker';

Answer 1

Correct syntax would be

update job
set job_title = 'Head of Technology',
    start_date = '26-JUN-17, 08:00'
where office = 'T06'
      and start_date = '05-FEB-09, 08:00'
      and staff_id =(select staff_id
                     from staff
                     where last_name = 'Parker'
                    );

However, it might need to be modified ( START_DATE condition is strange).

Also, it is unclear what START_DATE datatype is. Should be DATE , but your code suggests a string ( VARCHAR2 ).

---

Alternative #1 (note TO_DATE ) function:

update job
set job_title = 'Head of Technology',
    start_date = to_date('26-JUN-17, 08:00', 'dd-mon-yy, hh24:mi')
where office = 'T06'
      and start_date = to_date('05-FEB-09, 08:00', 'dd-mon-yy, hh24:mi')
      and staff_id =(select staff_id
                     from staff
                     where last_name = 'Parker'
                    );

---

Alternative #2 (note CASE and absence of START_DATE in WHERE clause):

update job
set job_title = 'Head of Technology',
    start_date = case when start_date = to_date('05-FEB-09, 08:00', 'dd-mon-yy, hh24:mi')
                           then         to_date('26-JUN-17, 08:00', 'dd-mon-yy, hh24:mi')
                      else start_date
                 end
where office = 'T06'
      and staff_id =(select staff_id
                     from staff
                     where last_name = 'Parker'
                    );

Answer 2

I would use EXISTS :

UPDATE JOB
    SET JOB_TITLE = 'Head of Technology'
        OFFICE = 'T06',
        START_DATE = '26-JUN-17, 08:00'
WHERE START_DATE = '05-FEB-09, 08:00' AND
      OFFICE = 'T06' AND
      EXISTS (SELECT 1
              FROM STAFF
              WHERE JOB.STAFF_ID = STAFF.STAFF_ID AND
                    STAFF.LAST_NAME = 'Parker' 
             );

Answer 3

The most native way is to use updatable join view

Simple make you join and select all relevant columns, than add UPDATE modifying the join.

update (
 select job.*
 FROM JOB
 JOIN STAFF
 ON JOB.STAFF_ID = STAFF.STAFF_ID
 WHERE STAFF.LAST_NAME = 'Parker')
set JOB_TITLE = 'Head of Technology',
START_DATE = '26-JUN-17, 08:00'

The only requirement is that the column STAFF_ID in STAFF table is backed with a unique index (eg primary key).

Without this you get the ERROR ORA-01779: cannot modify a column which maps to a non key-preserved table

This way of UPDATE is very usefull if you need to update with a value from the joined table (not your case).