Split a column with comma delimiter - sql

Question

I have a table with 3 columns with the data given below.
ID | Col1 | Col2 | Status
1 8007590006 8002240001,8002170828 I
2 8002170828 8002000004 I
3 8002000001 8002240001 I
4 8769879809 8002000001 I
5 8769879809 8002000001 I
Col2 can contain multiple comma delimited values. I need to update status to C if there is a value in col2 that is also present in col1.
For example, for ID = 1, col2 contains 8002170828 which is present in Col1, ID = 2. So, status = 'C'
From what I tried, I know it won't work where there are multiple values as I need to split that data and get individual values and then apply update.
UPDATE Table1
SET STATUS = 'C'
WHERE Col1 IN (SELECT Col2 FROM Table1)

Answer 1

If you are using SQL Server 2016 or later, then STRING_SPLIT comes in handy:
WITH cte AS (
SELECT ID, Col1, value AS Col2
FROM Table1
CROSS APPLY STRING_SPLIT(Col2, ',')
)
UPDATE t1
SET Status = 'C'
FROM Table1 t1
INNER JOIN cte t2
ON t1.Col1 = t2.Col2;
Demo

Answer 2

This answer is intended as a supplement to Tim's answer
As you don't have the native string split that came in 2016 we can make one:
CREATE FUNCTION dbo.STRING_SPLIT
(
#List NVARCHAR(MAX),
#Delimiter NVARCHAR(255)
)
RETURNS TABLE
WITH SCHEMABINDING
AS
RETURN
(
SELECT y.i.value('(./text())[1]', 'nvarchar(4000)') as value
FROM
(
SELECT x = CONVERT(XML, '<i>'
+ REPLACE(#List, #Delimiter, '</i><i>')
+ '</i>').query('.')
) AS a CROSS APPLY x.nodes('i') AS y(i)
);
GO
--credits to sqlserverperfomance.com for the majority of this code - https://sqlperformance.com/2012/07/t-sql-queries/split-strings
Now Tim's answer should work out for you, so I won't need to repeat it here
I chose an xml based approach because it performs well and your data seems sane and won't have any xml chars in it. If it ever will contain xml chars like > that will break the parsing they should be escaped then unescaped after split
If you aren't allowed to make functions you can extract everything between the RETURNS and the GO, insert it into Tim's query,tweak the variable names to be column names and it'll still work out