Convert varchar MMDDYYYY to MM/DD/YYYY datetime and select the most recent date only - sql

Question

Okay, so I have kind of a weird issue... the dates in the table have been entered in as string values MMDDYYYY and I'm trying to have the displayed as MM/DD/YYYY in a report and only select the most recent date pertaining to an ID, because some ID's may have multiple dates.
Example of my table:
ID | MyDate |
------+----------+
1 | 01302014 |
1 | 04222014 |
2 | 01302014 |
What I want to see when I select and insert into a temp table is this:
ID | MyDate |
------+-----------+
1 | 4/22/2014 |
2 | 1/30/2014 |
I know that storing dates as string values is a poor practice especially when storing them as MMDDYYYY, but does anyone have a solution to this nightmare?
EDIT
I forgot to mention that some fields might be NULL. Not sure if that makes a difference or not, but I think it does if I try to flip the dates using Right, Left, Convert.

Answer 1

This question is for almost a year ago, nut probably someone can find it useful.
You need to CONVERT your string to DATE format and use a ROW_NUMBER function to window your result set.
Create table
DECLARE #tbl TABLE(Id INT, myDate VARCHAR(8))
Sample data
INSERT #tbl
SELECT 1 , '01302014' UNION ALL
SELECT 1 , '04222014' UNION ALL
SELECT 2 , '01302014'
Query
;WITH C AS(
SELECT ROW_NUMBER() OVER (PARTITION BY Id ORDER BY CONVERT(DATETIME, (SUBSTRING(myDate, 5, 4) + '.' + SUBSTRING(myDate, 1, 2) + '.' + SUBSTRING(myDate, 3, 2)), 101) DESC) AS Rn
,Id
,CAST(CONVERT(DATETIME, (SUBSTRING(myDate, 5, 4) + '.' + SUBSTRING(myDate, 1, 2) + '.' + SUBSTRING(myDate, 3, 2)), 101) AS DATE) AS myDate
FROM #tbl
)
SELECT Id, myDate
FROM C
WHERE Rn = 1
SQLFiddle Demo

Answer 2

Using a CONVERT like the following code snippet will work on any SQL Server regardless of language and/or locale configuration.
DECLARE #OldDate varchar(8);
SELECT #OldDate = '04252012';
SELECT CONVERT(datetime, substring(#OldDate,5,4) + '-' + substring(#OldDate,1,2) + '-' + substring(#OldDate,3,2) + 'T00:00:00')

Answer 3

You could try this:
convert(date,SUBSTRING (MyDate,1,2)+'/'+SUBSTRING (MyDate,3,2)+'/'+SUBSTRING (MyDate,5,4),101)

Answer 4

Select CONVERT(datetime,RIGHT('01302014',4) +
LEFT('01302014',2) +
SUBSTRING('01302014',3,2))
'2014-01-30 00:00:00.000'
;with Cte as (Select Id,CONVERT(datetime,RIGHT(MyDate,4)+LEFT(MyDate,2)+SUBSTRING(MyDate,3,2)) as sDate, C=ROW_NUMBER()
over(PARTITION By Id Order by MyDate desc)
From #Temp)
select *
from Cte
where C=1

Answer 5

First do a conversion to a datetime datatype, then convert it to a format you wish to:
select id, convert(varchar, max(convert(datetime,right(mydate, 4)+left(mydate,4))), 101)
from #t
group by id
Although I can't understand why would it not suffice to just convert it do datetime and leave the formatting where it belongs, to the client.

Answer 6

Select id,convert(varchar(11),cast(dateValue as Date),101)
From
(
Select id,MAX(cast(MyDate As Date)) as dateValue
From tableName
Group By id
) t

Answer 7

The simplest solution is mySQL str_to_date() function.
STR_TO_DATE(`MyDate`, '%m%d%Y')
This will convert it to a DATETIME which you then format as required
DATE_FORMAT(STR_TO_DATE(`MyDate`, '%m%d%Y'), '%c/%e/%Y')

Answer 8

Complete Query:
Select ID, Case When IsDate(RIGHT(MyDate,4)+LEFT(MyDate,2)+SUBSTRING(MyDate,3,2)) = 1
THEN Convert(varchar(10), Convert(datetime, RIGHT(MyDate,4)+LEFT(MyDate,2)+SUBSTRING(MyDate,3,2)), 101)
ELSE Null END AS MyDate FROM YourTable a where Case When IsDate(RIGHT(MyDate,4)+LEFT(MyDate,2)+SUBSTRING(MyDate,3,2)) = 1
THEN Convert(varchar(10), Convert(datetime, RIGHT(MyDate,4)+LEFT(MyDate,2)+SUBSTRING(MyDate,3,2)), 101)
ELSE Null END = (Select Max(Case When IsDate(RIGHT(MyDate,4)+LEFT(MyDate,2)+SUBSTRING(MyDate,3,2)) = 1
THEN Convert(varchar(10), Convert(datetime, RIGHT(MyDate,4)+LEFT(MyDate,2)+SUBSTRING(MyDate,3,2)), 101)
ELSE Null END)
FROM YourTable b
Where a.ID = b.ID
)

Answer 9

This is a modified version from Dimitris Kalaitzis' answer.
First, you will need to convert your MyDate into String. The data for example (01302014) is not treated as a string and the leading zero will be removed when you convert it. Therefore, use CAST to make MyDate as a String and add a leading 0 to it. Then you find the right 8 characters so to get rid of the leading zero for months from Oct to Dec.
Here is the code that should work for you:
CONVERT(Date, SUBSTRING(RIGHT('0' + CAST(MyDate AS VARCHAR(10)), 8), 1, 2) + '/' + SUBSTRING(RIGHT('0' + CAST(MyDate AS VARCHAR(10)), 8), 3, 2) + '/' + SUBSTRING(RIGHT('0' + CAST(MyDate AS VARCHAR(10)), 8), 5, 4), 101)
Hope this helps.

Answer 10

You first have to add the slashes to be able to convert it to a date, use STUFF
Then convert it to a DATE and select the MAX group by ID
Query:
SELECT ID, FORMAT(MAX(CONVERT(DATE,STUFF(STUFF(MyDate,3,0,'/'),6,0,'/'))),'MM/dd/yyyy') AS MyDate FROM TableName
GROUP BY ID