I have 2 tables that I'm unioning and want to custom order using ORDER BY CASE
but I keep getting the ORA-01785: ORDER BY item must be the number of a SELECT-list expression error.
My 2 tables each have a column named "VISIT", containing (something similar to) the following data:
FollowUp table: BASELINE, 1_MONTH, 2_MONTH
Procedure table: PROCEDURE
I want to union these tables and sort in the following order: BASELINE, PROCEDURE, 1_MONTH, 2_MONTH
Here is what I think should work:
SELECT VISIT
FROM FollowUp
UNION
SELECT VISIT
FROM Procedure
ORDER BY
CASE VISIT
WHEN 'BASELINE' THEN 1
WHEN 'PROCEDURE' THEN 2
WHEN '1_MONTH' THEN 3
WHEN '2_MONTH' THEN 4
ELSE 5 END
However I'm getting the 01785 error. I've also tried replacing CASE VISIT
with CASE 1
and get the same error. Thank you for the help!
Try doing this with a subquery:
select visit
from ((SELECT VISIT
FROM FollowUp
) union
(SELECT VISIT
FROM Procedure
)
) t
ORDER BY
CASE VISIT
WHEN 'BASELINE' THEN 1
WHEN 'PROCEDURE' THEN 2
WHEN '1_MONTH' THEN 3
WHEN '2_MONTH' THEN 4
ELSE 5 END;
If you do not need duplicate removal, then use union all
.
Try this:
SELECT x.visit,
CASE x.VISIT
WHEN 'BASELINE' THEN 1
WHEN 'PROCEDURE' THEN 2
WHEN '1_MONTH' THEN 3
WHEN '2_MONTH' THEN 4
ELSE 5
END
sort_by
FROM (SELECT VISIT FROM FollowUp
UNION ALL
SELECT VISIT FROM Procedure) x
ORDER BY SORT_BY
尝试这个:
SELECT VISIT, CASE VISIT WHEN 'BASELINE' THEN 1 WHEN 'PROCEDURE' THEN 2 WHEN '1_MONTH' THEN 3 WHEN '2_MONTH' THEN 4 ELSE 5 END ORDERFIELD FROM FollowUp UNION SELECT VISIT, CASE VISIT WHEN 'BASELINE' THEN 1 WHEN 'PROCEDURE' THEN 2 WHEN '1_MONTH' THEN 3 WHEN '2_MONTH' THEN 4 ELSE 5 END ORDERFIELD FROM Procedure ORDER BY ORDERFIELD
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.