Extracting more than one date from a text field - sql-server-2008

Question

I have a SQL query that I am using that works perfectly for what I am needing at extracting the first date in a text field. This is a free form text field that is tied to a status that when the right conditions align my query looks for a date and if it is in the correct format it extracts this date.
Sometimes the date will be input as a range of dates or a comma separated list of dates. I would like to know if there is a way to extract the last date in the case of a date range or the other dates in a list of dates?
The current query has 3 steps in temp tables for extracting the date here are snippets for each step.
In the first step it looks for the word 'proposed' and grabs a number of characters after:
,SUBSTRING(al.Comments,
PATINDEX('%proposed%',al.Comments)+9,17) [DateFirstPass]
In the second step the query it extracts the date:
,LEFT(
SUBSTRING(p1.DateFirstPass, PATINDEX('%[0-9/]%', p1.DateFirstPass), 10), --string (only numbers and forward slash) MAX of 10 chars (mm/dd/yyyy)
PATINDEX('%[^0-9/]%', SUBSTRING(p1.DateFirstPass, PATINDEX('%[0-9/]%', p1.DateFirstPass), 10) + 'X')-1) --char length after negating nonvalid characters '%[^0-9/]%'
[DateSecondPass]
In the last pass it adds in the year if it is missing:
CASE
WHEN ISDATE(p2.DateSecondPass) = 1
THEN CAST(p2.DateSecondPass AS DATE)
WHEN ISDATE(p2.DateSecondPass + '/' + this.yr) = 1
THEN p2.DateSecondPass + '/' + this.yr --Adds missing year
END [DateThirdPass]
FROM
#ProposedDateParse2 p2
CROSS JOIN (VALUES (CAST(YEAR(GETDATE()) AS varchar(4)))) this(yr)

Answer 1

Grab a copy of patternSplitCM
Here's the code:
-- PatternSplitCM will split a string based on a pattern of the form
-- supported by LIKE and PATINDEX
--
-- Created by: Chris Morris 12-Oct-2012
CREATE FUNCTION dbo.PatternSplitCM
(
#List VARCHAR(8000) = NULL,
#Pattern VARCHAR(50)
) RETURNS TABLE WITH SCHEMABINDING
AS
RETURN
WITH numbers AS (
SELECT TOP(ISNULL(DATALENGTH(#List), 0))
n = ROW_NUMBER() OVER(ORDER BY (SELECT NULL))
FROM
(VALUES (0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) d (n),
(VALUES (0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) e (n),
(VALUES (0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) f (n),
(VALUES (0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) g (n))
SELECT
ItemNumber = ROW_NUMBER() OVER(ORDER BY MIN(n)),
Item = SUBSTRING(#List,MIN(n),1+MAX(n)-MIN(n)),
[Matched]
FROM (
SELECT n, y.[Matched], Grouper = n - ROW_NUMBER() OVER(ORDER BY y.[Matched],n)
FROM numbers
CROSS APPLY (
SELECT [Matched] = CASE WHEN SUBSTRING(#List,n,1) LIKE #Pattern THEN 1 ELSE 0 END
) y
) d
GROUP BY [Matched], Grouper
Solution against a variable:
DECLARE #string varchar(8000) =
'Blah blah 3/1/2017, 12/19/2018,1/2/2020,1111/11111/1111/111/111 blah blah';
SELECT TOP (1) Item
FROM dbo.patternSplitCM(#string, '[0-9/]')
WHERE [Matched] = 1 AND ISDATE(item) = 1
ORDER BY -ItemNumber;
Results:
item
------
1/2/2020
Example against a table:
DECLARE #table table (someid int identity, sometext varchar(1000));
INSERT #table(sometext) VALUES
('Blah blah 3/1/2017, 12/19/2018,1/2/2020,1111/11111/1111/111/111 blah blah'),
('Yada yada 1/1/12, 12/31/1999 call me at 555-1212!');
SELECT t.someid, getLastDate.Item
FROM #table t
CROSS APPLY
(
SELECT TOP (1) Item
FROM dbo.patternSplitCM(t.sometext, '[0-9/]')
WHERE [Matched] = 1 AND ISDATE(item) = 1
ORDER BY -ItemNumber
) getLastDate;
Results:
someid Item
----------- -----------
1 1/2/2020
2 12/31/1999