在 Oracle SQL 中执行 MERGE 时，如何更新 SOURCE 中不匹配的行？

Question

我有一个main 数据库和一个report 数据库，我需要将一个表从main 同步到report。

但是，当 main 数据库中的项目被删除时，我只想在 report 数据库中设置一个 IsDeleted 标志。

有什么优雅的方法可以做到这一点？

我目前正在使用 MERGE 语句，如下所示：

MERGE INTO report.TEST target
USING (SELECT * FROM main.TEST) source
   ON (target.ID = source.ID)
WHEN MATCHED THEN
    UPDATE SET (target... = source...)
WHEN NOT MATCHED THEN
    INSERT (...) VALUES (source...)
;

WHEN NOT MATCHED 语句为我提供了来自main 的所有新值，但我还想更新来自report 的所有旧值。

我正在使用 Oracle PL/SQL。

Answer 1

您可以使用单独的 UPDATE 语句来做到这一点

UPDATE report.TEST target
SET    is Deleted = 'Y'
WHERE  NOT EXISTS (SELECT 1
                   FROM   main.TEST source
                   WHERE  source.ID = target.ID);

我不知道有什么方法可以将它整合到您的 MERGE 语句中。

Answer 2

下面的答案是将数据合并到同一张表中

MERGE INTO YOUR_TABLE d
USING (SELECT 1 FROM DUAL) m
    ON ( d.USER_ID = '123' AND d.USER_NAME= 'itszaif') 
WHEN NOT MATCHED THEN
        INSERT ( d.USERS_ID, d.USER_NAME)
        VALUES ('123','itszaif');

该命令检查USER_ID和USER_NAME是否匹配，如果不匹配则插入。

Answer 3

MERGE INTO target
USING
(
    --Source data
    SELECT id, some_value, 0 deleteMe FROM source
    --And anything that has been deleted from the source
    UNION ALL
    SELECT id, null some_value, 1 deleteMe
    FROM
    (
        SELECT id FROM target
        MINUS
        SELECT id FROM source
    )
) source
   ON (target.ID = source.ID)
WHEN MATCHED THEN
    --Requires a lot of ugly CASE statements, to prevent updating deleted data
    UPDATE SET target.some_value =
        CASE WHEN deleteMe=1 THEN target.some_value ELSE source.some_value end
    ,isDeleted = deleteMe
WHEN NOT MATCHED THEN
    INSERT (id, some_value, isDeleted) VALUES (source.id, source.some_value, 0)

--Test data
create table target as
select 1 ID, 'old value 1' some_value, 0 isDeleted from dual union all
select 2 ID, 'old value 2' some_value, 0 isDeleted from dual;

create table source as
select 1 ID, 'new value 1' some_value, 0 isDeleted from dual union all
select 3 ID, 'new value 3' some_value, 0 isDeleted from dual;


--Results:
select * from target;

ID  SOME_VALUE   ISDELETED
1   new value 1  0
2   old value 2  1
3   new value 3  0

Answer 4

merge into x as target using y as Source on target.ID = Source.ID
when not matched by target then insert
when matched then update
when not matched by source and target.ID is not null then
update whatevercolumn = 'isdeleted' ;