Question

I have the following query:

select      count(L.ID) from        LA inner join L on (LA.leadid = L.ID) where       L.status = 5 and         L.city = 'cityname' and         Date(LA.Datetime) < Date_Sub(Now(), INTERVAL 6 MONTH); 

which looks for records with status 5 in a particular city that are older than 6 months (the date for which is stored in LA). This returns about 4k results. I would like to update the value of the status to 1 on each of those records, and so my update looks like:

update      L, LA set         L.status = 1 where       L.status = 5  and         L.city = 'cityname'  and         Date(LA.SomeDatetime) < Date_Sub(Now(), INTERVAL 6 MONTH); 

but it stalls out and locks the db. I suspect there is a problem because there is no join, but I try something like:

update      L, LA from        L inner join LA on (L.OID = LA.leadid) set         L.status = 1 where       L.status = 5  and         L.syscity = 'cityname'  and         Date(LA.SomeDatetime) < Date_Sub(Now(), INTERVAL 6 MONTH); 

and it obviously won’t work because there is no ‘from’ in an update.

edit> I’m using MySQL

Answer 1

update      L set         L.status = 1 where       L.status = 5  and         L.city = 'cityname'  and         EXISTS (   select * from LA    where Date(LA.SomeDatetime) < Date_Sub(Now(), INTERVAL 6 MONTH)   and LA.leadid = L.ID )