Presto检查是否为NULL并返回默认值(NVL模拟) [英] Presto check if NULL and return default (NVL analog)

问题描述

Presto DB中是否有NVL的类似物?

Is there any analog of NVL in Presto DB?

我需要检查字段是否为NULL并返回默认值.

I need to check if a field is NULL and return a default value.

我这样解决这个问题:

SELECT
  CASE 
    WHEN my_field is null THEN 0 
    ELSE my_field 
  END
FROM my_table

但是我很好奇是否有可以简化此代码的东西.

But I'm curious if there is something that could simplify this code.

推荐答案

ISO SQL函数是 COALESCE

The ISO SQL function for that is COALESCE

coalesce(my_field,0)

https://prestodb.io/docs/current/functions/conditional.html

P.S. COALESCE 可以与多个参数一起使用.它将返回第一个(从左开始)非NULL参数，或者返回NULL(如果找不到).

P.S. COALESCE can be used with multiple arguments. It will return the first (from the left) non-NULL argument, or NULL if not found.

例如

coalesce (my_field_1,my_field_2,my_field_3,my_field_4,my_field_5)

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