尝试更新.如果它没有修改任何表示它不存在的行，那么执行插入操作.显然，您在事务中执行此操作.

Try to do an UPDATE. If it doesn't modify any row that means it didn't exist, so do an insert. Obviously, you do this inside a transaction.

如果您不想将额外的代码放在客户端，您当然可以将其包装在一个函数中.您还需要一个循环来处理这种想法中非常罕见的竞争条件.

You can of course wrap this in a function if you don't want to put the extra code on the client side. You also need a loop for the very rare race condition in that thinking.

文档中有一个例子:http:///www.postgresql.org/docs/9.3/static/plpgsql-control-structures.html，底部的示例 40-2.

There's an example of this in the documentation: http://www.postgresql.org/docs/9.3/static/plpgsql-control-structures.html, example 40-2 right at the bottom.

这通常是最简单的方法.你可以用规则做一些魔法，但它可能会变得更加混乱.我建议在任何一天都采用函数内包装方法.

That's usually the easiest way. You can do some magic with rules, but it's likely going to be a lot messier. I'd recommend the wrap-in-function approach over that any day.

这适用于单行或几行值.如果您正在处理大量行，例如来自子查询的行，您***将其拆分为两个查询，一个用于 INSERT，一个用于 UPDATE(当然作为适当的连接/子选择 - 无需编写您的主要过滤两次)

This works for single row, or few row, values. If you're dealing with large amounts of rows for example from a subquery, you're best of splitting it into two queries, one for INSERT and one for UPDATE (as an appropriate join/subselect of course - no need to write your main filter twice)