using charindex in a substring to trim a string - sql

Question

There is a column name from which I want to use to make a new column.
example:
name
asd_abceur1mz_a
asd_fxasdrasdusd3mz_a
asd_abceur10yz_a
asd_fxasdrasdusd15yz_a
The length of the column is not fixed so I assumed i have to use charindex to have a reference point from which I could trim.
What i want: at the end there is always z_a, and i need to place in a separate column the left part from z_a like this:
nameNew
eur1m
usd3m
eur10y
usd15y
The problem is that the number (in this example 1, 3, 10, 15) has 1 or two digits. I need to extract the information from name to nameNew.
After that i was thinking to make it easier to read and to output it like this:
eur_1m
usd_3m
eur_10y
usd_15y
I tried using a combination of substring and charindex, but so far without success.
SELECT *
, SUBSTRING(name, 1, ( CHARINDEX('z_a', NAME) - 1 )) AS nameNew
FROM myTable
This is for the first step, trimming the string, for the 2nd step (making it easier to read) I don't know how to target the digit and place an _.
Any help would be appreciated. Using sql server 2012
edit:
First of all thank you for your time and solutions. But your queries more or less even if they are working for 1 or 2 digits have the same problem. Consider this situation:
name
ab_dertEUR03EUR10YZ_A
if eur is two times in the string, then how can I eliminate this? Sorry for not includding this in my original post but i forgot that situation is possible and now that's a problem.
edit:
test your queries here, on this example:
http://www.sqlfiddle.com/#!3/21610/1
Please note that at the end it can be any combination of 1 or 2 digits and the letter y or m.
Ex: ab_rtgtEUR03EUR2YZ_A , ab_rtgtEUR03EUR2mZ_A, ab_rtgtEUR03EUR20YZ_A, ab_rtgtEUR03EUR20mZ_A
Some values for testing:
('ex_CHFCHF01CHF10YZ_A'), ('ab_rtgtEUR03EUR2YZ_A'), ('RON_asdRON2MZ_A'),
('tg_USDUSD04USD5YZ_A');
My understanding of your queries is that they perform something simillar to this (or at least they should)
ex_CHFCHF01CHF10YZ_A -> ex_CHFCHF01CHF10Y -> Y01FHC10FHCFHC -> Y01FHC -> CHF01Y -> CHF_01Y
RON_asdRON2MZ_A -> RON_asdRON2M -> M2NORdsa_ron -> M2NOR -> RON2M -> RON_2M

Answer 1

This works for one or two digits:
stuff(case
when name like '%[0-9][0-9]_z[_]a'
then left(right(name, 9), 6)
when name like '%[0-9]_z[_]a'
then left(right(name, 8), 5)
end, 4, 0, '_')

Answer 2

You can use a combination of substring , reverse and charindex.
SQL Fiddle
select substring(namenew,1,3) + '_' + substring(namenew, 4, len(namenew))
from (
select
case when name like '%[0-9][0-9]_z[_]a' then
reverse(substring(reverse(name), charindex('a_z',reverse(name)) + 3, 6))
when name like '%[0-9]_z[_]a' then
reverse(substring(reverse(name), charindex('a_z',reverse(name)) + 3, 5))
end as namenew
from myTable
) t

Answer 3

Try it like this:
declare #tbl TABLE(name VARCHAR(100));
insert into #tbl VALUES
('asd_abceur1mz_a')
,('asd_fxasdrasdusd3mz_a')
,('asd_abceur10yz_a')
,('asd_fxasdrasdusd15yz_a')
,('ab_dertEUR03EUR10YZ_A');
WITH CutOfThreeAtTheEnd AS
(
SELECT LEFT(name,LEN(name)-3) AS nameNew
FROM #tbl
)
,Max6CharsFromEnd AS
(
SELECT RIGHT(nameNew,6) AS nameNew
FROM CutOfThreeAtTheEnd
)
SELECT nameNew
,FirstNumber.Position
,Parts.*
,Parts.FrontPart + '_' + Parts.BackPart AS FinalString
FROM Max6CharsFromEnd
CROSS APPLY
(
SELECT MIN(x)
FROM
(
SELECT CHARINDEX('0',nameNew,1) AS x
UNION SELECT CHARINDEX('1',nameNew,1)
UNION SELECT CHARINDEX('2',nameNew,1)
UNION SELECT CHARINDEX('3',nameNew,1)
UNION SELECT CHARINDEX('4',nameNew,1)
UNION SELECT CHARINDEX('5',nameNew,1)
UNION SELECT CHARINDEX('6',nameNew,1)
UNION SELECT CHARINDEX('7',nameNew,1)
UNION SELECT CHARINDEX('8',nameNew,1)
UNION SELECT CHARINDEX('9',nameNew,1)
) AS tbl
WHERE x>0
) AS FirstNumber(Position)
CROSS APPLY(SELECT SUBSTRING(nameNew,FirstNumber.Position,1000) AS BackPart
,SUBSTRING(nameNew,FirstNumber.Position-3,3) AS FrontPart) AS Parts
this is the result:
nameNew Position BackPart FrontPart FinalString
ceur1m 5 1m eur eur_1m
dusd3m 5 3m usd usd_3m
eur10y 4 10y eur eur_10y
usd15y 4 15y usd usd_15y
EUR10Y 4 10Y EUR EUR_10Y