Using IndexOf and/Or Substring to parse data into separate columns - tsql

Question

I am working on migrating data from one database to another for a hospital. In the old database, the doctor's specialty IDs are all in one column (swvar_specialties), each separated by commas. In the new database, each specialty ID will have it's own column (example: Specialty1_PrimaryID, Specialty2_PrimaryID, Specialty3_PrimaryID, etc). I am trying to export the data out of the old database and separate these into these separate columns. I know I can use indexof and substring to do this - I just need help with the syntax.
So this query:
Select swvar_specialties as Specialty1_PrimaryID
From PhysDirectory
might return results similar to 39,52,16. I need this query to display Specialty1_PrimaryID = 39, Specialty2_PrimaryID = 52, and Specialty3_PrimaryID = 16 in the results. Below is my query so far. I will eventually have a join to pull the specialty names from the specialties table. I just need to get this worked out first.
Select pd.ref as PrimaryID, pd.swvar_name_first as FirstName, pd.swvar_name_middle as MiddleName,
pd.swvar_name_last as LastName, pd.swvar_name_suffix + ' ' + pd.swvar_name_degree as NameSuffix,
pd.swvar_birthdate as DateOfBirth,pd.swvar_notes as AdditionalInformation, 'images/' + '' + pd.swvar_photo as ImageURL,
pd.swvar_philosophy as PhilosophyOfCare, pd.swvar_gender as Gender, pd.swvar_specialties as Specialty1_PrimaryID, pd.swvar_languages as Language1_Name
From PhysDirectory as pd

Answer 1

The article Split function equivalent in T-SQL? provides some details on how to use a split function to split a comma-delimited string.
By modifying the table-valued function in presented in this article to provide an identity column we can target a specific row such as Specialty1_PrimaryID:
/*
Splits string into parts delimitered with specified character.
*/
CREATE FUNCTION [dbo].[SDF_SplitString]
(
#sString nvarchar(2048),
#cDelimiter nchar(1)
)
RETURNS #tParts TABLE (id bigint IDENTITY, part nvarchar(2048) )
AS
BEGIN
if #sString is null return
declare #iStart int,
#iPos int
if substring( #sString, 1, 1 ) = #cDelimiter
begin
set #iStart = 2
insert into #tParts
values( null )
end
else
set #iStart = 1
while 1=1
begin
set #iPos = charindex( #cDelimiter, #sString, #iStart )
if #iPos = 0
set #iPos = len( #sString )+1
if #iPos - #iStart > 0
insert into #tParts
values ( substring( #sString, #iStart, #iPos-#iStart ))
else
insert into #tParts
values( null )
set #iStart = #iPos+1
if #iStart > len( #sString )
break
end
RETURN
END
Your query can the utilise this split function as follows:
Select
pd.ref as PrimaryID,
pd.swvar_name_first as FirstName,
pd.swvar_name_middle as MiddleName,
pd.swvar_name_last as LastName,
pd.swvar_name_suffix + ' ' + pd.swvar_name_degree as LastName,
pd.swvar_birthdate as DateOfBirth,pd.swvar_notes as AdditionalInformation,
'images/' + '' + pd.swvar_photo as ImageURL,
pd.swvar_philosophy as PhilosophyOfCare, pd.swvar_gender as Gender,
(Select part from SDF_SplitString(pd.swvar_specialties, ',') where id=1) as Specialty1_PrimaryID,
(Select part from SDF_SplitString(pd.swvar_specialties, ',') where id=2) as Specialty2_PrimaryID,
pd.swvar_languages as Language1_Name
From PhysDirectory as pd