[英]Oracle SQL Custom Sort with Union
我有2个表要合并,并想使用ORDER BY CASE
定制顺序,但我不断收到ORA-01785:ORDER BY项目必须是SELECT列表表达式错误的编号。
我的2个表都有一个名为“ VISIT”的列,其中包含(类似于)以下数据:
跟进表格:BASELINE,1_MONTH,2_MONTH
程序表:程序
我想合并这些表并按以下顺序排序:BASELINE,PROCEDURE,1_MONTH,2_MONTH
我认为这应该起作用:
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
但是我收到01785错误。 我也尝试用CASE VISIT
CASE 1
替换CASE VISIT
并得到相同的错误。 感谢您的帮助!
尝试使用子查询执行此操作:
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;
如果不需要重复删除,请使用union all
。
尝试这个:
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
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