Question

update tableA
set tableA.column1 = 'someValue'
where tableA.column2 in 
( select column3 from tableB where tableB.column4 in 
(
'valueA',
'valueB',
-- about 50 more records go here
)
)

When I run this, the database seems to hang. I am pretty new to sql, so I want to rule out (…or more likely rule in) the possibility that the problem is with my statement. I am running this on an oracle database using sqlDeveloper.

Answer 1

If the DB is appearing to “hang” it may well be that there are modifications to the data in another, uncommited session.

Try…

SELECT *
FROM   tableA
WHERE  tableA.column2 IN ( select .... )
FOR UPDATE NOWAIT;

and see if you get an:

ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired

Make sure you issue a ROLLBACK after that test.

If you do get the error, it indicates that another session has a lock on the data.