I want to get a substring in SQL Server from last sequence of a split on dot (.).
I have a column which contains file names such as hello.exe, and I want to find the extension of the file exactly as Path.GetExtension("filename") does in C#.
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5 Answers
You can use reverse along with substring and charindex to get what you're looking for:
select
reverse(substring(reverse(filename), 1,
charindex('.', reverse(filename))-1)) as FileExt
from
mytable
This holds up, even if you have multiple . in your file (e.g.-hello.world.exe will return exe).
So I was playing around a bit with this, and this is another way (only one call to reverse):
select
SUBSTRING(filename,
LEN(filename)-(CHARINDEX('.', reverse(filename))-2), 8000) as FileExt
from
mytable
This calculates 10,000,000 rows in 25 seconds versus 29 seconds for the former method.
3 Comments
marc_s
+1 good call ! I was wondering if there way any easy way to deal with multiple '.' in the file name, without resorting to messy character counting and parsing - well done!
Rajesh
charindex('.', reverse(filename))-1 fails when there is no dot in filename. used charindex('.', reverse(filename))
Alessandro De Simone
in Mysql you can use SUBSTRING_INDEX, for example: SUBSTRING_INDEX(file_name, '.', -1), maybe there is something similar to sql-server
DECLARE @originalstring VARCHAR(100)
SET @originalstring = 'hello.exe'
DECLARE @extension VARCHAR(50)
SET @extension = SUBSTRING(@originalstring, CHARINDEX('.', @originalstring) + 1, 999)
SELECT @extension
That should do it, I hope! This works as long as you only have a single '.' in your file name - separating the file name from the extension.
Marc
1 Comment
Phil
This is a good answer IF you are 100% sure there is only one period (Fullstop) in the originalstring variable. Otherwise, the approved is better.
Try this
SELECT RIGHT(
'C:\SomeRandomFile\Filename.dat',
CHARINDEX(
'.',
REVERSE(
'C:\SomeRandomFile\Filename.dat'
),
0)
-1)
Comments
Same as accepted answer, but I've added a condition to avoid error when filename is null or when filename has no extension (no point):
select
reverse(substring(reverse(filename), 1,
charindex('.', reverse(filename))-1)) as FileExt
from
mytable
where
filename is not null
and charindex('.',filename) > 0
Comments
The following SQL request adressed most of the edge cases in my weird database where many files didn't have extensions.
select distinct reverse(left(reverse(fileNameWithExtension), charindex('.', reverse(fileNameWithExtension)) - 1))
from myTable
where charindex('.', reverse(fileNameWithExtension)) - 1 > 0 and charindex('.', reverse(fileNameWithExtension)) - 1 < 7 and fileNameWithExtension is not null
