Find a specific substring using Transact-SQL - sql

Question

I need to pull a specific substring from a string of the form:
foo=abc;bar=def;baz=ghi
For example, how would I get the value of "bar" from that string?

Answer 1

You can use charindex and substring. For example, to search for the value of "baz":
declare #str varchar(128)
set #str = 'foo=abc;bar=def;baz=ghi'
-- Make sure #str starts and ends with a ;
set #str = ';' + #str + ';'
select substring(#str,
charindex(';baz=',#str) + len(';baz='),
charindex('=',#str,charindex(';baz=',#str)) - charindex(';baz=',#str) - 1)
Or for the value of "foo" at the start of the string:
select substring(#str,
charindex(';foo=',#str) + len(';foo='),
charindex('=',#str,charindex(';foo=',#str)) - charindex(';foo=',#str) - 1)
Here's a UDF to accomplish this (more readable version inspired by BlackTigerX's answer):
create function dbo.FindValueInString(
#search varchar(256),
#name varchar(30))
returns varchar(30)
as
begin
declare #name_start int
declare #name_length int
declare #value_start int
declare #value_end int
set #search = ';' + #search
set #name_start = charindex(';' + #name + '=',#search)
if #name_start = 0
return NULL
set #name_length = len(';' + #name + '=')
set #value_start = #name_start + #name_length
set #value_end = charindex(';', #search, #value_start)
return substring(#search, #value_start, #value_end - #value_start)
end
As you can see, this isn't easy in Sql Server :) Better do this in the client language, or normalize your database so the substrings go in their own columns.

Answer 2

I have a generalized solution that works for this problem:
CREATE FUNCTION [dbo].[fn_StringBetween]
(
#BaseString varchar(max),
#StringDelim1 varchar(max),
#StringDelim2 varchar(max)
)
RETURNS varchar(max)
AS
BEGIN
DECLARE #at1 int
DECLARE #at2 int
DECLARE #rtrn varchar(max)
SET #at1 = CHARINDEX(#StringDelim1, #BaseString)
IF #at1 > 0
BEGIN
SET #rtrn = SUBSTRING(#BaseString, #at1
+ LEN(#StringDelim1), LEN(#BaseString) - #at1)
SET #at2 = CHARINDEX(#StringDelim2, #rtrn)
IF #at2 > 0
SET #rtrn = LEFT(#rtrn, #at2 - 1)
END
RETURN #rtrn
END
so if you run (just wrap your original string to be searched with ';' at beginning and end):
PRINT dbo.fn_StringBetween(';foo=abc;bar=def;baz=ghi;', ';bar=', ';')
you will get 'def' returned.

Answer 3

look into the PATINDEX function. It has wildcard matching which should help you..

Answer 4

you can use this function
alter function FindValue(#txt varchar(200), #find varchar(200))
returns varchar(200)
as
begin
declare
#firstPos int,
#lastPos int
select #firstPos = charindex(#find, #txt), #lastPos = charindex(';', #txt, #firstPos+5)
select #lastPos = len(#txt)+1 where #lastPos = 0
return substring(#txt, #firstPos+len(#find)+1, #lastPos-#firstPos-len(#find)-1)
end
select dbo.FindValue('foo=abc;bar=def;baz=ghi', 'bar')
update: was not using the length of #find

Answer 5

this is assuming that the string will have the same string format just substitute the column name for the 'foo=abc;bar=def;baz=ghi'
select substring('foo=abc;bar=def;baz=ghi',patindex('%bar=%','foo=abc;bar=def;baz=ghi')+4, len('foo=abc;bar=def;baz=ghi')-patindex('%;baz=%','foo=abc;bar=def;baz=ghi')-4)

Answer 6

This can achieve in simple way
DECLARE #str VARCHAR(30)
DECLARE #start INT
SET #str='foo=abc;bar=def;baz=ghi'
SET #start=CHARINDEX('bar',#str)
PRINT SUBSTRING(#str,#start,3)