Oracle Merge：如果不匹配则删除并插入

Question

我有一个简单的查询，但只有一部分让我困惑：

我有以下算法：

merge into table_1 table_2
on table_1.val1 = table_2.val1
when matched and table_1.val2 = table_2.val2
   then merge
when matched and table_1.val2 != table_2.val2
   then delete and insert ( I AM NOT SURE NOW TO DO THIS)
when not matched
   then insert;

你可以帮我解决删除并插入或告诉我一个方法吗？

Answer 1

您不能在WHEN MATCHED THEN UPDATE子句中插入。你只能在这里删除。如果你可以更新，为什么还需要删除然后插入？像这样：

merge into table_1 
using table_2 on (table_1.val1 = table_2.val1)
when matched then 
     update set table_1.val3 = 
                case when table_1.val2 = table_2.val2 
                     then table_1.val3 
                else table_2.val3 end
when not matched then insert ...

从下面的评论中我想你需要这样的东西：

1）没有引用table_1的外键 2）禁用table_1中的主键val2 3）更新table_1设置val2 = null;
4）运行合并
5）从table_1删除val2为空;
6）启用table_1中的主键