Help with two goofy queries

Question

This is for SQL 2005 - 2012. I was given these specs. There are no indexes on the two tables
This first one I have working, but wondering if anyone has any ideas to try and make it more efficient
IF OBJECT_ID('tempdb..#temp')IS NOT NULL
DROP TABLE #temp;
--IF DDORSC = ‘XFR’ and DDORBT = ‘XFR’ and pos1 = X,Y,Z and pos3 = '-' and pos4 <> X THEN
-- Move 16 ‘X’s starting at position 4 in field DDTRCE
select * into #Temp from
(SELECT 'X2-Y1234567890123451234', 'XFR', 'XFR' UNION ALL
SELECT 'Y2-Y1234567890123451234', 'XFR', 'XFR' UNION ALL
SELECT 'Z2-Y1234567890123451234', 'X2FR', 'XFR' UNION ALL
SELECT 'X2-X1234567890123451234', 'XF3R', 'XFR' UNION ALL
SELECT 'Y2-X12345678901234512354', 'XFR', 'XFR' UNION ALL
SELECT 'Z2-X1234567890123451234', 'XFR', 'XFR' UNION ALL
SELECT 'W2-X1234567890123451234', 'XFR', 'XFR' UNION ALL
SELECT 'Q2RX1234567890123451234', 'XFR', 'XFR' UNION ALL
SELECT 'Z2EW1234567890123451234', 'XFR', 'XFR') d (DDTRCE, DDORSC, DDORBT)
Update #Temp
SET DDTRCE = REPLACE(DDTRCE, substring(DDTRCE, 4, 16), 'XXXXXXXXXXXXXXXX')
WHERE DDORSC = 'XFR' and DDORBT = 'XFR' and
(DDTRCE like 'X%' or DDTRCE like 'Y%' or DDTRCE like 'Z%') and
DDTRCE like '__-%' and DDTRCE NOT like '___X%'
Select * from #Temp
This second one I am just stuck. No idea how to select 15 consecutive digits where the first digit is not a 0.
IF OBJECT_ID('tempdb..#temp2')IS NOT NULL
DROP TABLE #temp;
--IF HMPGMN = ‘AT01007’ and HMOLDF has more than 15 consecutive digits, and the consecutive
--digits is > 99,999,999,999,999 (14 digits) THEN mast consecutive digits just leaving the last 4
select * into #Temp2 from
(SELECT 'X2-Y1234567890123451234', 'AT01007' UNION ALL
SELECT '1234567890123451234', 'AT01007' UNION ALL
SELECT 'Y1234567890123451234', 'AT01007' UNION ALL
SELECT 'X2-X1234567890123451234', 'AT01007' UNION ALL
SELECT 'Z2EW1234567890123451234', 'AT01006') d (HMOLDF, HMPGMN)
Update #Temp2
Select * from #Temp2

Answer 1

Came of up with this for #2. It does not 100% work. I know that HMOLDF is varchar(20). So if the field had 20 digits, it would mask 15 and leave 5 unmasked. But it is the best that I can come up with
Update #Temp2
SET HMOLDF = REPLACE(HMOLDF, substring(HMOLDF, patindex('%[1-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]%',HMOLDF), 15), 'XXXXXXXXXXXXXXX')
WHERE patindex('%[1-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]%',HMOLDF) > 0
and HMPGMN = 'AT01007'