Check duplicates in nvarchar column of table in SQL Server

Question

I have two tables: Import and ImportItem . One Import has multiple ImportItem . One ImportItem has one Import .

In my ImportItem I have a column CountryIDs . It's an NVARCHAR(MAX) . It is a string of IDs with ; as delimiter so for example: 3; 4; 5;... 3; 4; 5;...

I need to determine duplicates, actually if I run on a duplicate I need to raise some error. So 3; 4; 3; 3; 4; 3; ... 3 is duplicate.

I have a split function (I did not write that function, I was told to use it) that splits a string ( nvarchar ) and returns a table with columns ItemNo and Item (from previous example it would return 1 for ItemNo and 3 for Item , 2 for ItemNo and 4 for Item .

I need to write a procedure. My question is, how can I iterate through that column of CountryIDs for given ImportItem ID and split it and check for duplicates?

Answer 1

You can use apply to get the list of items, something like this:

select ii.itemno, s.c, count(*) as cnt
from importitem ii apply
     dbo.split(ii.countryids) as s(c)
group by ii.itemno, s.c
having count(*) > 1;

Once you have the list, you can decide how to process it in the stored procedure.