Session Locks... Please help this is urgent...

Question

Hi,
I've created web application in ASP.NET and I'm connecting to one of our Oracle server which resides in other country. I only have read access to it. I can only do select statements.
After couple of months that the application was running, their database admin told me that my application was creating session locks in the database.
I only have 4 select statements that's connection to their oracle server. Below one of the query that I'm using.
IDataReader r = null;
try
using (OracleConnection conn = new OracleConnection(this.ConnectionString))
string _return;
conn.Open();
OracleCommand command = new OracleCommand("select site from mashreq_employees where employee_code='" + emplid + "'", conn);
r = this.ExecuteReader(command);
if (r.Read())
_return = r.ToString();
else
_return = "";
return _return;
finally
if (r != null)
r.Close();
My question is, Can I create Session Locks even if I'm only using SELECT STATEMENT?
They send me the screen shot of their Enterprise Manager but I cannot paste it here. The Lock Type was "TX".
Please help me...
Thanks,
Liezl

Answer 1

I didn't see a FOR UPDATE in the code you posted but I don't know what the rest of your code/application does. For all I know the below code adds a FOR UPDATE at the end?
OracleCommand command = new OracleCommand("select site from mashreq_employees where employee_code='" + emplid + "'", conn); Am trying to say that just because you're using SELECT only doesn't necessarily mean it's non-destructive, in nobody elses way "read-only", it is still possible to do a SELECT FOR UPDATE if you have the SELECT privilege for a table which might explain any TX locks for your session.
SQL> create table a1 as (select * from user_tables);
Table created.
SQL> create table b1 as (select * from user_tables);
Table created.
SQL> select * from b1 where table_name = 'A1' for update;Now go to another session and try to update the table
update b1 set table_name = 'Z';Session will hang, until original session either commits or rolls back. Investigating further:
SQL> select session_id, object_id from v$locked_object;
SESSION_ID  OBJECT_ID
        25      17552
SQL> column object_name format a30
SQL> select owner, object_id, object_name from dba_objects where object_id = 17552
OWNER                           OBJECT_ID OBJECT_NAME
TESTUSER                            17552 B1
SQL> select sid, type, lmode, id1, id2 from v$lock where sid = 25;
       SID TY      LMODE        ID1        ID2
        25 TM          3      17552          0     <---- see the 17552 which is the B1 table and session 25 which is the session that did the FOR UPDATE?
        25 TX          6     589824        424So, see if you can track down which session is creating the locks from the data dictionary tables and whether it is your code.