sql - 如何 UPSERT(更新或插入表？)

Question

UPSERT 操作更新或插入表中的行，具体取决于表是否已有与数据匹配的行:

if table t has a row exists that has key X:
    update t set mystuff... where mykey=X
else
    insert into t mystuff...

由于 Oracle 没有特定的 UPSERT 语句，那么执行此操作的最佳方法是什么？

Answer 1

MERGE statement合并两个表之间的数据。使用双允许我们使用这个命令。请注意，这不受并发访问保护。

create or replace
procedure ups(xa number)
as
begin
    merge into mergetest m using dual on (a = xa)
         when not matched then insert (a,b) values (xa,1)
             when matched then update set b = b+1;
end ups;
/
drop table mergetest;
create table mergetest(a number, b number);
call ups(10);
call ups(10);
call ups(20);
select * from mergetest;

A                      B
---------------------- ----------------------
10                     2
20                     1