在 SQL 服务器中将上个月设置为“mmm”格式的默认值？

Question

I want to create a temporary table where the period is always the previous month in abbreviation. For example today the default value would be 'Sep'.

I have this code but it throws me errors after trying add other values to the table:

create table tmp_hfm 
( 
    Entity_Code nvarchar(15),
    HFM_Account nvarchar(15),
    HFM_Segment nvarchar(15),
    Period date default format(month(getdate()) - 1, 'mmmm')
)

The error I get:

Conversion failed when converting date and/or time from character string.

Can someone advise on this please?

Answer 1

Try this:

CREATE TABLE tmp_hfm (
  Entity_Code NVARCHAR(15),
  HFM_Account NVARCHAR(15),
  HFM_Segment NVARCHAR(15),
  Period CHAR(3) DEFAULT FORMAT(DATEADD(MONTH, -1, GETDATE()), 'MMM')
);

If you need to specify culture, you can add another parameter after 'MMM':

CREATE TABLE tmp_hfm (
  Entity_Code NVARCHAR(15),
  HFM_Account NVARCHAR(15),
  HFM_Segment NVARCHAR(15),
  Period CHAR(3) DEFAULT FORMAT(DATEADD(MONTH, -1, GETDATE()), 'MMM', 'en-us')
);

Here is an SQL Fiddle for you: link

Answer 2

I don't understand what you want to do. You have defined Period as a date column. FORMAT() returns a string. They are not compatible.

Perhaps you want period to be char(3) , with a default of format(dateadd(month, -1, getdate()), 'MMM') .

For "Sep", I would be inclined to use left(datename(month, dateadd(month, -1, getdate())), 3) , unless you have a reason for preferring the internationalization functionality of format() .