我怎样才能在 Postgres 9.5 中做一些更新插入

Question

我有一个简单的table:

NAME    | TIMESTAMP | AMOUNT
--------------------------
Name1   | 123       | 1
Name2   | 123       | 15
Name3   | 124       | 3
Name4   | 125       | 1

等等。现在我得到了一个新记录。如果名称和时间戳相等，我希望数量增加新记录的数量，否则应该插入新记录。

类似于：

INSERT INTO test.data (NAME, TIMESTAMP, AMOUNT) values ('Name1', 123, 4) 
IF not EXIST; OTHERWISE UPDATE test.data set AMOUNT + NEWAMOUNT where TIMESTAMP = oldTimestamp and NAME = oldName

这是否可以通过使用 Postgres 9.5 的一个简单 sql 查询以某种方式实现？

谢谢

Answer 1

使用新的 on conflict 子句：

INSERT INTO test.data (NAME, TIMESTAMP, AMOUNT) 
values ('Name1', 123, 4) 
on conflict (name, timestamp) 
  do update 
    set AMOUNT + excluded.NEWAMOUNT

这要求您在 (name, timestamp)

上定义了唯一约束（或索引）

如果您不想让 (name, timestamp) 独一无二，您可以使用可写的 CTE：

with new_values (name, timestamp, amount) as (
  values ('Name1', 123, 4)
), changed as (
  update data 
     set amount = amount + t.amount
  from new_values nv 
   where data.name = nv.name
     and data.timestamp = nv.timestamp
  returning *
)
insert into data (name, timestamp, amount)
select name, timestamp, amount
from new_values
where not exists (select 1 from changed);

请注意（与 on conflict 解决方案不同）这对并发更新不安全，并且您可能有竞争条件

Answer 2

with t as (
  update test.data set 
    AMOUNT = AMOUNT + 4 
  where 
    NAME = 'Name1' and TIMESTAMP = 123 
  returning 
    *) -- In the t we have list of updated rows (if any)

insert into test.data(NAME, TIMESTAMP, AMOUMT)
  select 'Name1', 123, 4
  where not exists (select * from t); -- Insert new row in rows was not updated

我怎样才能在 Postgres 9.5 中做一些更新插入

How can I do some kind of upsert within Postgres 9.5

sql

postgresql

upsert