insert into does not work

Why doesn't the query below work:

INSER开发者_运维百科T INTO [ProcessStatus] ([ProcessId])
SELECT TMP.[ProcessId]

FROM (
SELECT DISTINCT 
     [ProcessId]
FROM [Process]
) TMP

error message is (returns added):

Subquery returned more than 1 value.
This is not permitted when the subquery follows =, !=, <, <= , >, >= 
or when the subquery is used as an expression.

There may be a buggy trigger on the ProcessStatus table.

Assuming [Process] only has the one field (or any others auto increment), you do not need the sub query. Try:

insert into [ProcessStatus] ([ProcessId])
select distinct 
     [ProcessId]
FROM [Process]

EDIT: if you were just wondering why the error message, it should work, are you sure that is where it's failing?

There doesn't seem to be anything wrong with that. It works for me:

CREATE TABLE #ProcessStatus (ProcessID INTEGER)
CREATE TABLE #Process (ProcessID INTEGER)

INSERT INTO #Process VALUES(1)
INSERT INTO #Process VALUES(2)

INSERT INTO #ProcessStatus (ProcessId)
SELECT TMP.ProcessId
FROM (
SELECT DISTINCT 
     ProcessId
FROM #Process
) TMP

(2 row(s) affected)

Are you absolutely sure about what's going on?