SQL Server 2012将日期时间数据从varchar转换为Date部分

Question

Have researched a lot, both on this site, and others, but still don't have a valid solution. I have a column of varchar datatype, it contains DateTime data. I need to store only the Date portion in a Date type column. Tried different ways of Cast, Convert, and other functions, but still haven't been able to make it work.

Basically I want to convert this

Tue Apr 26 2016 13:54:53 GMT+0200 (CEST)

to

04/26/2016

Answer 1

Assuming your Day and Month part is always 3 characters long this can be done simply as this:

DECLARE @d VARCHAR(100)='Tue Apr 26 2016 13:54:53 GMT+0200 (CEST)';
SELECT CONVERT(DATE,SUBSTRING(@d,4,12),109);

If this was to easy one would have to find the blank(s) with CHARINDEX , but I don't think so...

The format code 109 means mon dd yyyy hh:mi:ss:mmmAM (or PM) Details here .

And be aware that formats containing language depending parts are directly sent by the devil to create never ending pain... This will not work on a server with a different language setting!

Answer 2

Declare @String varchar(max) = 'Tue Apr 26 2016 13:54:53 GMT+0200 (CEST)'
Select cast(Substring(@String,12,4)+Substring(@String,4,7) as date)

Returns

2016-04-26

Answer 3

Okay a few things here you have a field that looks to be psuedo ISO 8601 but is not the standard. The first question will be: "Where does this come from?" Typically you don't have the 'Tue' or 'GMT' or '(CEST)' in a standard and the offset from Greenwich Meantime is in the format (+/-)##:## NOT (+/-)####. SQL and many other formats can easily accept a standardized string in the ISO 8601 format. Good brief here: https://www.w3.org/TR/NOTE-datetime

That being said you can easily get what you want with a little know how:

DECLARE 
    @S VARCHAR(128) = 'Tue Apr 26 2016 13:54:53 GMT+0200 (CEST)'
,   @Valid VARCHAR(128)

--Legitimate ISO 8601 string:
SELECT @Valid = RTRIM(LTRIM(REPLACE(STUFF(STUFF(@S, 1, 4, ''), LEN(@S)-12, 12, ':00'), 'GMT', '')))
SELECT @Valid

--Legitimate DateTimeOffset
SELECT CAST(@Valid AS DATETIMEOFFSET)

--Now that I have a legimiate DateTimeOffset I can downconvert easily
SELECT CAST(CAST(@Valid AS DATETIMEOFFSET) AS DATE)

--AND... Now that I have a legimate Date I can format it many different ways
SELECT CONVERT(VARCHAR, CAST(CAST(@Valid AS DATETIMEOFFSET) AS DATE), 101)

The real thing to realize here is there is magical conversion of DateTime using the convert function. But you may be wondering 'what if I want it to look different?'. Try this page:

http://www.sql-server-helper.com/tips/date-formats.aspx

I would be leery though of just finding the placement of were things appear to be coming from a string even though I can parse your example. If you are getting things not following a standard you should know why. The main reason being you may be able to get this to work for a specific instance but not be able to repeat this pattern over and over.