oracle - Update_or_insert（合并到）在 Oracle 中不起作用

Question

下面我的 UPDATE_OR_INSERT 代码有什么问题？

MERGE INTO EMAIL_LIST d USING (SELECT 'foo@gmail.com' EMAIL) s
    ON (d.EMAIL = s.EMAIL)
        WHEN MATCHED THEN
            UPDATE SET d.EMAIL = s.EMAIL
        WHEN NOT MATCHED THEN
            INSERT (EMAIL) VALUES (s.EMAIL);

给定表格：

CREATE TABLE EMAIL_LIST ( 
    EMAIL VARCHAR2 (100)  NOT NULL
);
ALTER TABLE EMAIL_LIST
    ADD CONSTRAINT PK_EMAIL_LIST PRIMARY KEY ( EMAIL ) ;

错误

错误报告：

SQL 错误：ORA-00923：FROM 关键字未在预期的位置找到 00923。00000 -“FROM 关键字未在预期的位置找到”

Answer 1

几件事；

您需要从某些东西中选择常数，在 Oracle 的情况下，DUAL；

MERGE INTO EMAIL_LIST d 
USING 
    (SELECT 'foo@gmail.com' EMAIL FROM DUAL) s
ON (d.EMAIL = s.EMAIL)
WHEN MATCHED THEN
    UPDATE SET d.EMAIL = s.EMAIL
WHEN NOT MATCHED THEN
    INSERT (EMAIL) VALUES (s.EMAIL);

此外，您无法在 d.EMAIL 上匹配并同时更新它。您的线路；

WHEN MATCHED THEN
    UPDATE SET d.EMAIL = s.EMAIL

无论如何都没有意义，因为 d.EMAIL 已经等于 s.EMAIL 或者匹配不会发生。删除WHEN MATCHED，您将完成工作；

MERGE INTO EMAIL_LIST d 
USING 
    (SELECT 'foo@gmail.com' EMAIL FROM DUAL) s
ON (d.EMAIL = s.EMAIL)
WHEN NOT MATCHED THEN
    INSERT (EMAIL) VALUES (s.EMAIL);