如何在 PL/SQL 中增量集成数据

Question

如何将两个不同表中的数据增量插入到另一个表中？

假设我有表 A 和 B，我想在表 C 中增量插入行。行应该只插入一次（如果该行已经存在，则不应插入任何内容）并且不能在表 C 中更新或删除。

我认为它可以在循环中使用游标，然后如果不匹配则合并并插入数据。我是否完全错了，因为我收到错误消息“表或视图不存在”。

for x in A --cursor with data from given table
        loop
        MERGE INTO C USING A
        ON (x.id = C.id)
        WHEN NOT MATCHED THEN
        insert(C.id, C.email, C.address) values(x.id, x.email, x.address);
        end loop;

for x in B --cursor with data from given table
            loop
            MERGE INTO C USING B
            ON (x.id = C.id)
            WHEN NOT MATCHED THEN
            insert(C.id, C.email, C.address) values(x.id, x.email, x.address);
            end loop;

Answer 1

Merge 采用 select 语句，而不是游标。某处你的代码有“光标A是选择...”，然后你尝试“使用（A）合并到表中......”但是合并需要一个实际的选择。正确的格式是“merge into c using(select ...) A”并去掉光标。

   merge into c 
   using ( select id, email, address 
             from a
         ) x
   on (x.id = c.id)
   when not matched then
        insert(c.id, c.email, c.address) 
        values(x.id, x.email, x.address);
 
merge into c 
   using ( select id, email, address 
             from b
         ) x
   on (x.id = c.id)
   when not matched then
        insert(c.id, c.email, c.address) 
        values(x.id, x.email, x.address);