Why does DB2 return -1 when deleting all rows in a table? - db2

Question

The question says it all. Using the Python API as an example:
import ibm_db
#setup stuff
conn = ibm_connect(DATABASE, user, password)
stmt = ibm_db.exec_immediate(conn, 'DELETE FROM sometable')
print(ibm_db.num_rows(stmt)) # prints -1
Why doesn't it print the actual count of rows deleted?

Answer 1

This is not an answer, really, just showing that the function does work and that SQLCODEs cause python exceptions. The fact that num_rows() does not work for you may indicate that the functionality may not be supported by the database you're connected to. You may want to describe your environment in detail: the DB2 server version and platform, whether it's a local or remote database, the DB2 client version (if different from the server) etc.
>>> import ibm_db
>>> conn = ibm_db.connect('TEST',user,password)
>>> stmt = ibm_db.exec_immediate(conn, 'create table t (f int)')
>>> print ibm_db.num_rows(stmt) # DDL statement - num_rows not applicable
-1
>>> stmt = ibm_db.exec_immediate(conn,'delete from t')
>>> print ibm_db.num_rows(stmt) # 0 rows deleted
0
>>> stmt = ibm_db.exec_immediate(conn,'delete from x') # nonexistent table - exception
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
Exception: [IBM][CLI Driver][DB2/LINUXX8664] SQL0204N "USER.X" is an undefined name. SQLSTATE=42704 SQLCODE=-204
>>> stmt = ibm_db.exec_immediate(conn,'insert into t(f) values (1),(2),(3)')
>>> print ibm_db.num_rows(stmt) # 3 rows inserted
3
>>> stmt = ibm_db.exec_immediate(conn,'delete from t')
>>> print ibm_db.num_rows(stmt) # 3 rows deleted
3
>>> ibm_db.close(conn)
True
>>>

Answer 2

A negative SQL Code in DB2 means an error:
SQL codes