Oracle SQL 查询未显示正确的值

Question

我有一个 table 包含以下列：

编号
技术
name_event
time_event

我使用以下查询 table 计算值的数量

    select  1, 'Folder' as "Technology", 'Status' as "Name_Event", count(dm1.id) as "number of items", max(TO_CHAR(TO_DATE('20000101','yyyymmdd')+(SYSDATE - dm1.time_event),'hh24:mi:ss')) as "Time in system" 
    from db dm1 join db dm2 on dm1.id = dm2.id
    where dm1.technology = 'Folder' and dm1.name_event = 'status1' and NOT EXISTS(SELECT 1 FROM db dm2 WHERE dm2.name_event = 'status2' and dm2.id = dm1.id)

我做了以下插入

    INSERT INTO DB(id, technology, name_event, time_event) VALUES(1,'Folder', 'status1', 01:00:00);
    INSERT INTO DB(id, technology, name_event, time_event) VALUES(2,'Folder', 'status1', 01:00:00);
    INSERT INTO DB(id, technology, name_event, time_event) VALUES(3,'Folder', 'status1', 01:00:00);
    INSERT INTO DB(id, technology, name_event, time_event) VALUES(4,'Folder', 'status1', 01:00:00);
    INSERT INTO DB(id, technology, name_event, time_event) VALUES(5,'Folder', 'status1', 01:00:00);
    INSERT INTO DB(id, technology, name_event, time_event) VALUES(6,'Folder', 'status1', 01:00:00);
    INSERT INTO DB(id, technology, name_event, time_event) VALUES(7,'Folder', 'status1', 01:00:00);
    INSERT INTO DB(id, technology, name_event, time_event) VALUES(8,'Folder', 'status1', 01:00:00);
    INSERT INTO DB(id, technology, name_event, time_event) VALUES(9,'Folder', 'status1', 01:00:00);
    INSERT INTO DB(id, technology, name_event, time_event) VALUES(10,'Folder', 'status1', 01:00:00);
INSERT INTO DB(id, technology, name_event, time_event) VALUES(4,'Folder', 'status2', 02:00:00);
INSERT INTO DB(id, technology, name_event, time_event) VALUES(1,'Folder', 'status2', 03:00:00);

我在status 1插入了10行，把2移到status 2，所以执行查询的时候status 1应该有8个item，但是结果是10...

我做错了什么？

Answer 1

您正在 table 中使用 2 个以上的插入，所以现在您总共有 10+2 个 12 个插入，要移动数据，请使用更新语句。

update db set name_event='status2' where id=4;
update db set name_event='status4' where id=1;

Answer 2

在您的查询中，您正在 joining dm2 但随后使用 NOT EXISTS 相关子查询（并在该子查询中使用相同的别名）。我无法用我的设置复制问题，但这肯定会混淆某些东西！因此，请尝试不使用第二个数据库副本，只保留 NOT EXISTS :

select  1, 'Folder' as "Technology", 'Status' as "Name_Event", count(dm1.id) as "number of items", max(TO_CHAR(TO_DATE('20000101','yyyymmdd')+(SYSDATE - dm1.time_event),'hh24:mi:ss')) as "Time in system" 
from db dm1 
where dm1.technology = 'Folder' and dm1.name_event = 'status1' and NOT EXISTS(SELECT 1 FROM db dm2 WHERE dm2.name_event = 'status2' and dm2.id = dm1.id)

Oracle SQL 查询未显示正确的值

Oracle SQL query doesn't show correct value

sql

oracle

select

count