Dealing with splitting strings in SQL - sql

Question

Currently I'm working on a project where we just added the ability to have multiple values stored within a field. Previously, it stored a single value, but now it contains multiple. Below is an example of what I'm talking about.
Ex. A person's name is passed in (John Smith). Now the user can pass in multiple people's names, delimited by a ';' (John Smith;John Doe;Jane Tandy).
My issue is that we have a data source for a drop down that currently feeds off this field. Below is the SQL for it.
Select Distinct Content
From LIB_DocumentAttribute A
inner join LIB_PublicDocument B on A.PublicDocumentId = B.PublicDocumentId
Where AttributeId = (Select AttributeId From LIB_Attribute Where FieldName='Author')
and B.Status = 'Approved'
This somewhat works now. Content is the field that contains the multiple names. Now when the drop down is loaded, it pulls back the concatenated string of names (the longer one from above). I want to break it apart for the data source. So far, my only ideas is to split out the data based on the ';'. However, I need to take that split out data and apply it to the table that returns the rest of the data. Below is where I have gotten to but have become stuck on.
CREATE TABLE #Authors
(
Content varchar(MAX)
)
CREATE TABLE #Temp1
(
Content varchar(MAX)
)
CREATE TABLE #Temp2
(
Content varchar(MAX)
)
CREATE TABLE #Temp3
(
Content varchar(MAX)
)
--Load Authors table to store all Authors
INSERT INTO #Authors
Select Distinct Content
From LIB_DocumentAttribute A
inner join LIB_PublicDocument B on A.PublicDocumentId = B.PublicDocumentId
Where AttributeId = (Select AttributeId From LIB_Attribute Where FieldName='Author')
and B.Status = 'Approved'
--Take multiple Authors separated by '; ' and add to Temp1
INSERT INTO #Temp1
SELECT REPLACE(Content, '; ', ';') FROM #Authors WHERE Content LIKE '%; %'
--Remove multiple Authors separated by '; ' from Authors table
DELETE FROM #Authors
WHERE Content LIKE '%; %'
--Take multiple Authors separated by ';' and add to Temp2
INSERT INTO #Temp2
SELECT Content FROM #Authors WHERE Content LIKE '%;%'
--Remove multiple Authors separated by ';' from Authors table
DELETE FROM #Authors
WHERE Content LIKE '%;%'
--Somewhow split data and merge back together
DROP TABLE #Authors
DROP TABLE #Temp1
DROP TABLE #Temp2
DROP TABLE #Temp3
Edit:
So in the end, I came up with a solution that utilized some of the pieces that Kumar suggested. I created a function for splitting the string as he suggested and added some personal changes to make it work. Mind you this is in a table return function, with the table called #Authors, and it has one column called Content.
BEGIN
DECLARE #Temp TABLE
(
Content varchar(MAX)
)
--Load Authors table to store all Authors
INSERT INTO #Authors
Select Distinct Content
From LIB_DocumentAttribute A
inner join LIB_PublicDocument B on A.PublicDocumentId = B.PublicDocumentId
Where AttributeId = (Select AttributeId From LIB_Attribute Where FieldName='Author')
--Take multiple Authors separated by ', ' and add to Temp
INSERT INTO #Temp
SELECT REPLACE(Content, ', ', ',')
FROM #Authors;
--Remove multiple Authors separated by ', ' from Authors table
DELETE FROM #Authors
WHERE Content LIKE '%,%';
--Readd multiple Authors now separated into Authors table
INSERT INTO #Authors
SELECT s.Content
FROM #Temp
OUTER APPLY SplitString(Content,',') AS s
WHERE s.Content <> (SELECT TOP 1 a.Content FROM #Authors a WHERE s.Content = a.Content)
RETURN
END

Answer 1

Check the demo in fiddler link http://sqlfiddle.com/#!3/390f8/11
Create table test(name varchar(1000));
Insert into test values('AAA BBB; CCC DDD; eee fff');
CREATE FUNCTION SplitString
(
#Input NVARCHAR(MAX),
#Character CHAR(1)
)
RETURNS #Output TABLE (
Item NVARCHAR(1000)
)
AS
BEGIN
DECLARE #StartIndex INT, #EndIndex INT
SET #StartIndex = 1
IF SUBSTRING(#Input, LEN(#Input) - 1, LEN(#Input)) <> #Character
BEGIN
SET #Input = #Input + #Character
END
WHILE CHARINDEX(#Character, #Input) > 0
BEGIN
SET #EndIndex = CHARINDEX(#Character, #Input)
INSERT INTO #Output(Item)
SELECT SUBSTRING(#Input, #StartIndex, #EndIndex - 1)
SET #Input = SUBSTRING(#Input, #EndIndex + 1, LEN(#Input))
END
RETURN
END
Declare #name varchar(100)
Declare #table as table(name varchar(1000))
Declare cur cursor for
Select name from test
Open cur
fetch next from cur into #name
while (##FETCH_STATUS = 0)
begin
Insert into #table
Select * from dbo.splitstring(#name,';')
fetch next from cur into #name
end
close cur
deallocate cur
Select * from #table

Answer 2

this might work.
drop table authors
GO
create table Authors (Author_ID int identity (1,1),name varchar (255), category varchar(255))
GO
insert into authors
(name,category)
select
'jane doe','nonfiction'
union
select
'Jules Verne; Mark Twain; O. Henry', 'fiction'
union
select
'John Smith; John Doe', 'nonfiction'
GO
DECLARE #table TABLE (
names VARCHAR(255)
,id INT
)
DECLARE #category VARCHAR(255)
SET #category = 'nonfiction'
DECLARE #Author_ID INT
DECLARE AuthorLookup CURSOR
FOR
SELECT Author_ID
FROM authors
WHERE category = #category
OPEN AuthorLookup
FETCH NEXT
FROM AuthorLookup
INTO #Author_ID
WHILE ##FETCH_STATUS = 0
BEGIN
IF (
SELECT CHARINDEX(';', NAME, 0)
FROM authors
WHERE Author_ID = #Author_ID
) = 0
BEGIN
INSERT INTO #table
SELECT NAME
,Author_ID
FROM authors
WHERE Author_ID = #Author_ID
END
ELSE
BEGIN
DECLARE #value VARCHAR(255)
SELECT #value = NAME
FROM authors
WHERE Author_ID = #Author_ID
WHILE len(#value) > 0
BEGIN
INSERT INTO #table
SELECT substring(#value, 0, CHARINDEX(';', #value, 0))
,#Author_ID
SELECT #value = replace(#value, substring(#value, 0, CHARINDEX(';', #value, 0) + 2), '')
IF CHARINDEX(';', #value, 0) = 0
BEGIN
INSERT INTO #table
SELECT #value
,#Author_ID
SET #value = ''
END
END
END
FETCH NEXT
FROM AuthorLookup
INTO #Author_ID
END
CLOSE AuthorLookup
DEALLOCATE AuthorLookup
SELECT *
FROM #table

Answer 3

You can create function to split your data
create function SplitString
(
#data nvarchar(max),
#sep char(1)
)
returns #result table (data nvarchar(max))
as
begin
declare #i int
while 1 = 1
begin
select #i = charindex(#sep, #data)
if #i = 0
begin
insert into #result
select #data
break
end
insert into #result
select rtrim(left(#data, #i - 1))
select #data = ltrim(right(#data, len(#data) - #i))
end
return
end
and use it like this:
select s.data
from test as t
outer apply SplitString(t.data,';') as s
If you're sure that you don't have special characters inside your data, you can also consider trick with xml:
;with cte as (
select
cast('<s>' + replace(data, ';', '</s><s>') + '</s>' as xml) as data
from test
)
select
t.c.value('.', 'nvarchar(max)') as data
from cte
outer apply data.nodes('s') as t(c)
sql fiddle demo