Extract Min Date from a string with several dates using SQL Server - sql-server

Question

I am trying to extract the min date from a varchar string.
The data in the field looks like this
QTY DIFFERENCE - PO LINE 6. 147 ON PO / 192 ON INVOICE
5/18/2016 4:18:52 PM by ROOFING\ebuchanan
ANDREW SANTORI ISSUED THIS PO, PLEASE SEND TO HIS QUE
5/21/2016 9:48:42 AM by ROOFING\knaylor
RE-ROUTED TO ATS
Using this code
SELECT
UISeq,
LEFT(SUBSTRING(Notes, PATINDEX('%[0-9/]%', Notes), 8000),
PATINDEX('%[^0-9/]%', SUBSTRING(Notes, PATINDEX('%[0-9/]%', Notes), 8000) + 'X') -1) as 'MaxDate'
FROM
bAPUI
WHERE
Notes IS NOT NULL
ORDER BY
UISeq
I get this result from the record above
6
I also get
01/01/2000
On other fields
How do I correct the code to only return the Min date within each record field?
UISeq MinDate
2 3
3 5
13 4/1/2016
15 1
17
18 4/15/2016
19 3
20 4/15/2016
40 05/22/16
43 05/22/16
54 5/18/16
John's post is beyond my current ability
I have created the function, here is the code to extract the data
Declare #Str varchar(max);
Select #Str as Notes, Min(Key_Value)
from bAPUI, [dbo].[SA-udf-Str-Parse](replace(#Str,char(13),' '),' ')
Where Key_Value like '%/%'
and len(Key_Value)>=10
What I am not understanding is how to get the bAPUI.Notes table/field into the select statement.

Answer 1

The following uses a string parser udf. Perhaps in your data, or even just in the example, there were chr(13)'s, so I had to perform a replace(), there could be other extended characters that may need to be trapped.
Declare #Str varchar(max)
Set #Str='QTY DIFFERENCE - PO LINE 6. 147 ON PO / 192 ON INVOICE
5/18/2016 4:18:52 PM by ROOFING\ebuchanan
ANDREW SANTORI ISSUED THIS PO, PLEASE SEND TO HIS QUE
5/21/2016 9:48:42 AM by ROOFING\knaylor
RE-ROUTED TO ATS'
Select * from [dbo].[udf-Str-Parse](replace(#Str,char(13),' '),' ')
Where Key_Value like '%/%'
and len(Key_Value)>=10
Returns
Key_PS Key_Value
13 5/18/2016
28 5/21/2016
While with a quick change
Select Min(Key_Value) from [dbo].[udf-Str-Parse](replace(#Str,char(13),' '),' ')
Where Key_Value like '%/%'
and len(Key_Value)>=10
Returns
5/18/2016
There are millions of variations but here is mine.
CREATE FUNCTION [dbo].[udf-Str-Parse] (#String varchar(max),#delimeter varchar(10))
--Usage: Select * from [dbo].[udf-Str-Parse]('Dog,Cat,House,Car',',')
-- Select * from [dbo].[udf-Str-Parse]('John Cappelletti was here',' ')
-- Select * from [dbo].[udf-Str-Parse]('id26,id46|id658,id967','|')
Returns #ReturnTable Table (Key_PS int IDENTITY(1,1) NOT NULL , Key_Value varchar(500))
As
Begin
Declare #intPos int,#SubStr varchar(500)
Set #IntPos = CharIndex(#delimeter, #String)
Set #String = Replace(#String,#delimeter+#delimeter,#delimeter)
While #IntPos > 0
Begin
Set #SubStr = Substring(#String, 0, #IntPos)
Insert into #ReturnTable (Key_Value) values (#SubStr)
Set #String = Replace(#String, #SubStr + #delimeter, '')
Set #IntPos = CharIndex(#delimeter, #String)
End
Insert into #ReturnTable (Key_Value) values (#String)
Return
End
So to apply to your data
Select UISeq,
,MinDate=(Select Min(Key_Value) from [dbo].[udf-Str-Parse](replace(Notes,char(13),' '),' ') Where Key_Value like '%/%' and len(Key_Value)>=10)
FROM bAPUI
WHERE Notes IS NOT NULL
ORDER BYUISeq
I have no idea how this will perform on a large dataset

Answer 2

Super quick draft - Use CHARINDEX And LEFT to retrieve all characters up to the first space, then convert that text to a DATE, then use MIN to select the EARLIEST date.
select #str as string
,left(#str,CHARINDEX(' ',#str)) -- Get the position of the first space, then select all characters up to the space
,MIN(convert(date,left(#str,CHARINDEX(' ',#str)))) -- Convert the selected characters to a date and then use MIN to select earliest date