T-SQL 字符串到日期时间的转换

Question

I need to cast string values of the following formats to DateTime:

2042-04
2011-01

Is there an easy way to do this? I've tried CAST AND CONVERT without much luck.

Thanks!

Answer 1

try appending "-01" to the end of it and then doing the cast or convert

Answer 2

declare @S varchar(7)
set @S = '2042-04'

select cast(stuff(@S, 5, 1, '')+'01' as datetime)

YYYYMMDD is a safe format regardless of SET DATEFORMAT . YYYY-MM-DD is not. http://www.sommarskog.se/wishlist.html#YYYYMMDD

Answer 3

SELECT CAST('2011-01-01' AS DATETIME)
SELECT CONVERT(DATE , '2011-01-01')

It seems you need to add a 'day' to the string.

Answer 4

Declare @Table Table
(
    ColDateTime Varchar(100)
)
Insert into @Table
Select '2042-04' UNION ALL
Select '2011-01'

Select ColDateTime As VarcharCol,
Cast(
    substring(ColDateTime,0,charindex('-',ColDateTime))+substring(ColDateTime,charindex('-',ColDateTime)+1,len(ColDateTime))+'01'
As DateTime) As DateTimeCol
from @Table