I think you missed the point, if you are using "=" the subquery must 
return only ONE record. Using DISTINCT doesn't give you that.

If you use "IN", the sub query can return multiple records.

You can do:

DELETE
FROM
":WORK:Artiklar.DB"
WHERE
IDnr in
(
SELECT DISTINCT IDnr
FROM ":PRIV:ToDelete.DB"
)


You could also use this:

DELETE
FROM
":WORK:Artiklar.DB"
WHERE
IDnr =
(
SELECT  IDnr
FROM ":PRIV:ToDelete.DB"
where
Name = 'Apple'
)

But this will fail if there is more than one item with the Name "Apple" 
in the sub-table. Using DISTINCT will not help as it will only make sure 
that the column IDnr doesn't return dublicates, but it could still 
return more than one record.


An example where "=" will work

DELETE
FROM
":WORK:Artiklar.DB"
WHERE
IDnr =
(
SELECT  MAX(IDnr)
FROM ":PRIV:ToDelete.DB"
)

Anders



Den 2020-02-12 kl. 15:31, skrev Mark Bannister:
> Doesn't work with DISTINCT either.
> 
> On 2/11/2020 7:09 PM, Tom Krieg wrote:
>> I don't know much about local SQL but it won't work because the 
>> sub-query could return more than one result.
>>
>> try WHERE ID IN (SELECT id5 ... etc
>>
>> On 12/02/2020 5:21 am, Mark Bannister wrote:
>>> Do local sql delete queries not work at all when using a select 
>>> sub-query?
>>> DELETE FROM  ':PRIV:I0IPDIMXREF2.DB'
>>>
>>> WHERE (id =
>>> (SELECT id5
>>> FROM ':PRIV:__Sql_run68.db' )
>>> )
>>>
>>> Reports it works.  Doesn't delete anything.
>>> -- 
>>> Mark B
>>
>