Question

I am trying to insert data in table, but if it already exists in table, then it should not add.
This is the code, what I came up, but it still adds multiple data with same values.

insert into nol_art_izm([ART_ID],[DAT])
    select distinct
        v.id_art, {fn now()}
    from
        openxml(@hDoc, '/art_kompl/nol_voac') with #vc xd
        inner join nol_voac v on xd.id_art = v.id_art
    where
        not exists(select * from nol_art_izm where nol_art_izm.art_id=xd.id_art)

I want that there aren’t any duplicate “ART_ID” values

Answer 1

Try

insert into nol_art_izm([ART_ID],[DAT])
    select distinct
        v.id_art, {fn now()}
    from
        openxml(@hDoc, '/art_kompl/nol_voac') with #vc xd
        inner join nol_voac v on xd.id_art = v.id_art
        left join nol_art_izm n on n.art_id = v.id_art
    where n.art_id is null

Update:

Try using GROUP BY to avoid duplicate id_art values:

insert into nol_art_izm([ART_ID],[DAT])
    select
        v.id_art, MAX({fn now()})
    from
        openxml(@hDoc, '/art_kompl/nol_voac') with #vc xd
        inner join nol_voac v on xd.id_art = v.id_art
    where
        not exists(select * from nol_art_izm where nol_art_izm.art_id=xd.id_art)
    group by v.id_art

Please not that I have chosen the MAX function for aggregating the {fn now()} values (in case there are more such values per id_art). You might want to use another function.