带空字符串的SQL Coalesce

我有以下内容：

Select Coalesce(Other,Industry) Ind from registration

问题是Other可以是空字符串或NULL。我如何coalesce工作，以便如果Other是空字符串，Coalesce仍然返回Industry？

使用CASE表达式或NULLIF：

SELECT COALESCE(NULLIF(Other,''),Industry) Ind FROM registration

尝试这个

Select Coalesce(nullif(Other,''),Industry) Ind from registration

您也可以使用捷径知道NULL <> ''不会评估为TRUE...

CASE WHEN other <> '' THEN other ELSE industry END

逻辑如下：

• CASE WHEN 'fubar' <> '' THEN other ELSE industry END
  => CASE WHEN true THEN other ELSE industry END
  =>other

• CASE WHEN '' <> '' THEN other ELSE industry END
  => CASE WHEN false THEN other ELSE industry END
  =>industry

• CASE WHEN NULL <> '' THEN other ELSE industry END
  => CASE WHEN NULL THEN other ELSE industry END
  =>industry