Question

I’m trying to insert or update a single table using the MERGE command however I always get a “0 rows affected”. My goal is simple: if exists update, otherwise insert. What am I doing wrong?

Note: the table’s primary key is a combo key = [date]+sip+dip+port
where date is datetime and all other fields are int

merge iplog as t
using (SELECT * from iplog Where [date]='20120101' and sip=1 and dip=2 and port=80) as s
on t.[date]=s.[date] and t.sip=s.sip and t.dip=s.dip and t.port=s.port
when matched then
    update set t.size=t.size+s.size
when not matched then
    insert values ('20120101',1,2,80,1);

Answer 1

I think you’re wanting to insert a new value if there isn’t currently one matching by date, sip, dip and port, but it’s unclear what size you want in the UPDATE condition. I’ve picked 1:

create table iplog (
    [date] date not null,
    sip int not null,
    dip int not null,
    port int not null,
    size int not null
)
GO
merge iplog as t
using (SELECT '20120101' as [date] , 1 as sip , 2 as dip , 80 as port) as s
on t.[date]=s.[date] and t.sip=s.sip and t.dip=s.dip and t.port=s.port
when matched then
    update set t.size=t.size+1 --What should this be?
when not matched then
    insert values ('20120101',1,2,80,1);

select * from iplog

You’ll note that the source doesn’t reference the target table at all now.

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Side note – I’d recommend avoiding SQL keywords such as date as column names.