如何在oracle中使用SELECT查询创建一个空白/空列? [英] How to create a blank/empty column with SELECT query in oracle?

问题描述

我想用 oracle 中的选择"查询生成一个带有空白/空列的输出.我可以使用以下 sql 查询来实现这一点:

I want to generate an output with blank/empty column with a "Select" query in oracle. I'm able to achieve this with below sql query:

SELECT CustomerName AS Customer, "" AS Contact 
FROM Customers;

因此，当我在 sql 查询上方运行时，它返回一个表，其中包含两列Customer"列，其中包含内容，Contact"列没有内容或空白列.我想通过 oracle 查询实现相同的目标.任何帮助将不胜感激.

So when I run above sql query it returns a table with two columns "Customer" column with content in it and "Contact" column with no content or blank column. I want to achieve same with oracle query. Any help will be highly appreciated.

推荐答案

我认为你应该使用 null

I think you should use null

SELECT CustomerName AS Customer, null AS Contact 
FROM Customers;

记住甲骨文

将长度为零的字符值视为空值.

treats a character value with a length of zero as null.

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