合并到不匹配时插入 if 条件

Question

我有以下查询：

merge into A a 
using (select :1 as x, :2 as y from sys.dual) tmp 
on (a.x = tmp.x and 
    a.y = tmp.y) 
when matched then 
   update set a.z = case when :3 = 1 then :4 else null end 
when not matched then 
   insert 
   ( 
    x, 
    y, 
    z 
   )
   values 
   ( 
    :1, 
    :2, 
    case when :3 = 1 then :4 else null end
   )

这有效，但是当 :3 为 0 时插入了一条新记录。该记录的 z 值为空。如果 :3 为 0，我宁愿不插入记录。

有什么办法吗？

Answer 1

来自 11.1 的文档（对于较新的版本也是如此）：https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_9016.htm#SQLRF01606

Specify the where_clause if you want Oracle Database to execute the insert operation only if the specified condition is true. The condition can refer only to the data source table. Oracle Database skips the insert operation for all rows for which the condition is not true.

Answer 2

根据 [the 11.2 documentation] 你可以在插入子句上有一个 where 子句，所以你的合并语句会变成这样：

merge into A a 
using (select :1 as x, :2 as y from sys.dual) tmp 
on (a.x = tmp.x and 
    a.y = tmp.y) 
when matched then 
   update set a.z = case when :3 = 1 then :4 else null end 
when not matched then 
   insert 
   ( 
    x, 
    y, 
    z 
   )
   values 
   ( 
    :1, 
    :2, 
    case when :3 = 1 then :4 else null end
   )
   where :3 != 0 or :3 is null;

N.B。未经测试

合并到不匹配时插入 if 条件

merge into when not matched insert if condition

sql

oracle

insert-update