如果日期值为空，则将日期时间转换为字符串-保持原始日期时间格式

我的查询包含以下部分：

I have the following part of my query:

ISNULL(cast(fd.decision_date as varchar(20)), 'PENDING') as facility,
ISNULL(cast(cd.decision_date as varchar(20)), 'PENDING') as corporate,
ISNULL(cast(cb.creation_date as varchar(20)), 'PENDING') as billing

我的值最初是datetime数据类型，但我想做的是

My values are originally of datetime datatype, but what I want to do is return the word 'PENDING' if the value is NULL.

使用上面的代码，我的结果被 cast ed了到 varchar ，因此返回以下内容：

With the code above, my results are casted to a varchar, thus returning something like:

Aug 20 2013 9:35AM 

而不是 2013-08-20 09:35:54

建议将不胜感激。