how to substring of a string in SQL

Question

My data will be like that

IPDocument/XR/test_20120409_clearGAC.txt
IPDocument/XR/test_20120409_clearGAC_05.txt
IPDocument/XR/test_20120409_clearGAC_01.txt


        

Answer 1

SELECT SUBSTRING('IPDocument/XR/test_20120409_clearGAC.txt', CHARINDEX('09_','IPDocument/XR/test_20120409_clearGAC.txt')+3, 100)

result : clearGAC.txt

Answer 2

I assume that you want the _05 and _01 - the question is not clear.

DECLARE @var VARCHAR(250)

DECLARE @table TABLE ( val VARCHAR(250) )
INSERT  INTO @table
        SELECT  'IPDocument/XR/test_20120409_clearGAC_01.txt'
        UNION ALL
        SELECT  'IPDocument/XR/test_20120409_clearGAC_05.txt'
        UNION ALL
        SELECT  'IPDocument/XR/test_20120409_clearGAC.txt' 


SELECT  SUBSTRING(val, CHARINDEX('clearGAC', val), 50),
        SUBSTRING(SUBSTRING(val, CHARINDEX('_', val)+1, 50), CHARINDEX('_', SUBSTRING(val, CHARINDEX('_', val)+1, 50))+1, 50)
FROM    @table

Returns this:

clearGAC_01.txt
clearGAC_05.txt
clearGAC.txt

The third parameter in the CHARDINDEX can be larger than the length.

EDIT: I added logic if you don't know if clearGAC is the name

After reading your comment, you may just want this:

I am going to pass ClearGAC.txt and see if it's in the DB. this ClearGAC.txt may be named like above codes.

DECLARE @var VARCHAR(250)

DECLARE @table TABLE ( val VARCHAR(250) )
INSERT  INTO @table
        SELECT  'IPDocument/XR/test_20120409_clearGAC_01.txt'
        UNION ALL
        SELECT  'IPDocument/XR/test_20120409_clearGAC_05.txt'
        UNION ALL
        SELECT  'IPDocument/XR/test_20120409_clearGAC.txt' 


SELECT  *
FROM    @table
WHERE   val LIKE '%clearGAC%.txt'