tsql - 空日期返回无效日期

Question

尝试将日期字段中的 NULL 更改为空白结果，但它一直返回日期。当我需要满足以下条件时，我会这样做：

CASE WHEN closed = 'y' THEN Date ELSE '' END

我尝试过强制转换为 varchar 和其他东西，它要么抛出错误，要么什么都不做！

Answer 1

You should convert it to a varchar:

CASE WHEN closed = 'y' THEN LEFT(CONVERT(VARCHAR, Date, 120), 10) ELSE '' END

See How to convert DateTime to VarChar for more information.

Answer 2

A column in your result can only contain one type, it can't be both a date and a text field. You could convert your date to a string providing you no longer need it to be a date like so:

CASE WHEN closed = 'y' 
THEN CAST(Date AS VARCHAR) 
ELSE '' END