Sql Server string to date conversion

Question

I want to convert a string like this:

'10/15/2008 10:06:32 PM'

into the equivalent DATETIME value in Sql Server.

In Oracle, I would say this:

TO_DATE('10/15/2008 10:06:32 PM','MM/DD/YYYY HH:MI:SS AM')

This question implies that I must parse the string into one of the standard formats, and then convert using one of those codes. That seems ludicrous for such a mundane operation. Is there an easier way?

Answer 1

I found this article useful in creating my function that converts string values from .NET Datetime.ToString(...) back into SQL datetime. Tested it on 1000s of string dates in my system. Seems to work well. Hope this saves you time.

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:      Julian King
-- Create date: 3/14/2023
-- Description: Parses and returns a date from a variety of string formats
-- See: https://www.mssqltips.com/sqlservertip/1145/date-and-time-conversions-using-sql-server/
--      Thu Jul 01 2021 00:00:00 GMT-0400 (Eastern Daylight Time)
--      2018-04-16T00:00:00
--      2021-05-04T20:13:34.897781
--      2021-11-04 20:58:57.352836
--      4/17/2020 11:02:59 AM
--      January 13, 2020
-- =============================================
CREATE FUNCTION dbo.DateConvert
(
    @datestring VARCHAR(55)
)
RETURNS DATETIME
AS
BEGIN
    -- Declare the return variable here
    SET @datestring = RTRIM(LTRIM(@datestring))

    IF @datestring IS NULL
        RETURN CAST('1753-1-1' AS DATETIME)  
    
    IF @datestring = ''
        RETURN CAST('1753-1-1' AS DATETIME)

    -- Thu Jul 01 2021 00:00:00 GMT-0400 (Eastern Daylight Time)
    IF LEN(@datestring) > 30 AND @datestring LIKE '%GMT-%'
        SET @datestring = RTRIM(LTRIM(SUBSTRING(@datestring,5,20)))


    -- 2021-05-04T20:13:34.897781
    -- 2020-11-01T00:00:00
    IF @datestring LIKE '%T%'
        SET @datestring = REPLACE(@datestring,'T',' ')

    -- 2021-05-04 20:13:34.897781
    IF LEN(@datestring) = 26
        SET @datestring = SUBSTRING(@datestring,0,20)
    
    IF TRY_CONVERT(DATETIME,@datestring,101) IS NULL 
        RETURN CAST('1753-1-1' AS DATETIME) 
    ELSE
        RETURN CONVERT(DATETIME,@datestring,101) 

    RETURN CAST('1753-1-1' AS DATETIME)  
END
GO

Answer 2

The most upvoted answer here are guravg's and Taptronic's. However, there's one contribution I'd like to make.

The specific format number they showed from 0 to 131 may vary depending on your use-case (see full number list here), the input number can be a nondeterministic one, which means that the expected result date isn't consistent from one SQL SERVER INSTANCE to another, avoid using the cast a string approach for the same reason.

Starting with SQL Server 2005 and its compatibility level of 90, implicit date conversions became nondeterministic. Date conversions became dependent on SET LANGUAGE and SET DATEFORMAT starting with level 90.

Non deterministic values are 0-100, 106, 107, 109, 113, 130. which may result in errors.

---

The best option is to stick to a deterministic setting, my current preference are ISO formats (12, 112, 23, 126), as they seem to be the most standard for IT people use cases.

Convert(varchar(30), '210510', 12)                   -- yymmdd
Convert(varchar(30), '20210510', 112)                -- yyyymmdd
Convert(varchar(30), '2021-05-10', 23)               -- yyyy-mm-dd
Convert(varchar(30), '2021-05-10T17:01:33.777', 126) -- yyyy-mm-ddThh:mi:ss.mmm (no spaces)

Answer 3

Try this

Cast('7/7/2011' as datetime)

and

Convert(DATETIME, '7/7/2011', 101)

See CAST and CONVERT (Transact-SQL) for more details.

Answer 4

Short answer:

SELECT convert(date, '10/15/2011 00:00:00', 101) as [MM/dd/YYYY]

Other date formats can be found at SQL Server Helper > SQL Server Date Formats

Answer 5

This code solve my problem :

convert(date,YOUR_DATE,104)

If you are using timestamp you can you the below code :

convert(datetime,YOUR_DATE,104)

Answer 6

You can easily achieve this by using this code.

SELECT Convert(datetime, Convert(varchar(30),'10/15/2008 10:06:32 PM',102),102)

Answer 7

convert string to datetime in MSSQL implicitly

create table tmp 
(
  ENTRYDATETIME datetime
);

insert into tmp (ENTRYDATETIME) values (getdate());
insert into tmp (ENTRYDATETIME) values ('20190101');  --convert string 'yyyymmdd' to datetime


select * from tmp where ENTRYDATETIME > '20190925'  --yyyymmdd 
select * from tmp where ENTRYDATETIME > '20190925 12:11:09.555'--yyyymmdd HH:MIN:SS:MS

Answer 8

dateadd(day,0,'10/15/2008 10:06:32 PM')

Answer 9

Took me a minute to figure this out so here it is in case it might help someone:

In SQL Server 2012 and better you can use this function:

SELECT DATEFROMPARTS(2013, 8, 19);

Here's how I ended up extracting the parts of the date to put into this function:

select
DATEFROMPARTS(right(cms.projectedInstallDate,4),left(cms.ProjectedInstallDate,2),right( left(cms.ProjectedInstallDate,5),2)) as 'dateFromParts'
from MyTable

Answer 10

Use this:

SELECT convert(datetime, '2018-10-25 20:44:11.500', 121) -- yyyy-mm-dd hh:mm:ss.mmm

And refer to the table in the official documentation for the conversion codes.

Answer 11

Run this through your query processor. It formats dates and/or times like so and one of these should give you what you're looking for. It wont be hard to adapt:

Declare @d datetime
select @d = getdate()

select @d as OriginalDate,
convert(varchar,@d,100) as ConvertedDate,
100 as FormatValue,
'mon dd yyyy hh:miAM (or PM)' as OutputFormat
union all
select @d,convert(varchar,@d,101),101,'mm/dd/yy'
union all
select @d,convert(varchar,@d,102),102,'yy.mm.dd'
union all
select @d,convert(varchar,@d,103),103,'dd/mm/yy'
union all
select @d,convert(varchar,@d,104),104,'dd.mm.yy'
union all
select @d,convert(varchar,@d,105),105,'dd-mm-yy'
union all
select @d,convert(varchar,@d,106),106,'dd mon yy'
union all
select @d,convert(varchar,@d,107),107,'Mon dd, yy'
union all
select @d,convert(varchar,@d,108),108,'hh:mm:ss'
union all
select @d,convert(varchar,@d,109),109,'mon dd yyyy hh:mi:ss:mmmAM (or PM)'
union all
select @d,convert(varchar,@d,110),110,'mm-dd-yy'
union all
select @d,convert(varchar,@d,111),111,'yy/mm/dd'
union all
select @d,convert(varchar,@d,12),12,'yymmdd'
union all
select @d,convert(varchar,@d,112),112,'yyyymmdd'
union all
select @d,convert(varchar,@d,113),113,'dd mon yyyy hh:mm:ss:mmm(24h)'
union all
select @d,convert(varchar,@d,114),114,'hh:mi:ss:mmm(24h)'
union all
select @d,convert(varchar,@d,120),120,'yyyy-mm-dd hh:mi:ss(24h)'
union all
select @d,convert(varchar,@d,121),121,'yyyy-mm-dd hh:mi:ss.mmm(24h)'
union all
select @d,convert(varchar,@d,126),126,'yyyy-mm-dd Thh:mm:ss:mmm(no spaces)'

Answer 12

In SQL Server Denali, you will be able to do something that approaches what you're looking for. But you still can't just pass any arbitrarily defined wacky date string and expect SQL Server to accommodate. Here is one example using something you posted in your own answer. The FORMAT() function and can also accept locales as an optional argument - it is based on .Net's format, so most if not all of the token formats you'd expect to see will be there.

DECLARE @d DATETIME = '2008-10-13 18:45:19';

-- returns Oct-13/2008 18:45:19:
SELECT FORMAT(@d, N'MMM-dd/yyyy HH:mm:ss');

-- returns NULL if the conversion fails:
SELECT TRY_PARSE(FORMAT(@d, N'MMM-dd/yyyy HH:mm:ss') AS DATETIME);

-- returns an error if the conversion fails:
SELECT PARSE(FORMAT(@d, N'MMM-dd/yyyy HH:mm:ss') AS DATETIME);

I strongly encourage you to take more control and sanitize your date inputs. The days of letting people type dates using whatever format they want into a freetext form field should be way behind us by now. If someone enters 8/9/2011 is that August 9th or September 8th? If you make them pick a date on a calendar control, then the app can control the format. No matter how much you try to predict your users' behavior, they'll always figure out a dumber way to enter a date that you didn't plan for.

Until Denali, though, I think that @Ovidiu has the best advice so far... this can be made fairly trivial by implementing your own CLR function. Then you can write a case/switch for as many wacky non-standard formats as you want.

---

UPDATE for @dhergert:

SELECT TRY_PARSE('10/15/2008 10:06:32 PM' AS DATETIME USING 'en-us');
SELECT TRY_PARSE('15/10/2008 10:06:32 PM' AS DATETIME USING 'en-gb');

Results:

2008-10-15 22:06:32.000
2008-10-15 22:06:32.000

You still need to have that other crucial piece of information first. You can't use native T-SQL to determine whether 6/9/2012 is June 9th or September 6th.

Answer 13

Personally if your dealing with arbitrary or totally off the wall formats, provided you know what they are ahead of time or are going to be then simply use regexp to pull the sections of the date you want and form a valid date/datetime component.

Answer 14

SQL Server (2005, 2000, 7.0) does not have any flexible, or even non-flexible, way of taking an arbitrarily structured datetime in string format and converting it to the datetime data type.

By "arbitrarily", I mean "a form that the person who wrote it, though perhaps not you or I or someone on the other side of the planet, would consider to be intuitive and completely obvious." Frankly, I'm not sure there is any such algorithm.

Answer 15

This page has some references for all of the specified datetime conversions available to the CONVERT function. If your values don't fall into one of the acceptable patterns, then I think the best thing is to go the ParseExact route.

Answer 16

If you want SQL Server to try and figure it out, just use CAST CAST('whatever' AS datetime) However that is a bad idea in general. There are issues with international dates that would come up. So as you've found, to avoid those issues, you want to use the ODBC canonical format of the date. That is format number 120, 20 is the format for just two digit years. I don't think SQL Server has a built-in function that allows you to provide a user given format. You can write your own and might even find one if you search online.

Answer 17

For this problem the best solution I use is to have a CLR function in Sql Server 2005 that uses one of DateTime.Parse or ParseExact function to return the DateTime value with a specified format.