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Closing cx_Oracle connection while resolving database down

The following code cx_Oracleworks fine when the database is completed:

#!C:\Python27
import cx_Oracle

try:
    conn = cx_Oracle.connect("scott/tiger@oracle")

    try:
        curs = conn.cursor()
        curs.execute("SELECT dummy FROM sys.dual")
        print curs.fetchone()[0]
    finally:
        curs.close()
finally:
    conn.close()

But if the database does not work, when I run this script, it is created NameError:

Traceback (most recent call last):
  File "C:\Users\ArtMetzer\Documents\Code\Python\db_conn_test.py", line 14, in <module>
    conn.close()
NameError: name 'conn' is not defined

This makes sense to me: cx_OracleI could not create an instance of the connection, so the variable was connnever set and therefore has no method close().

In Python, what is the best way to ensure that the database connection is closed while still gracefully processing the database state down?

Doing something like the following seems like a huge shred to me:

finally:
    try:
        conn.close()
    except NameError:
        pass
+3
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2 answers

conn - None , finally. , , - , - . , open None, None :

#!C:\Python27
import cx_Oracle

conn = None
try:
    conn = cx_Oracle.connect("scott/tiger@oracle")

    try:
        curs = conn.cursor()
        curs.execute("SELECT dummy FROM sys.dual")
        print curs.fetchone()[0]
    finally:
        curs.close()
finally:
    if conn is not None:
        conn.close()
+4

( , )

:

#!C:\Python27
import cx_Oracle

try:
    conn = cx_Oracle.connect("scott/tiger@oracle")

    try:
        curs = conn.cursor()
        curs.execute("SELECT dummy FROM sys.dual")
        print curs.fetchone()[0]
    finally:
        curs.close()
        conn.close()
except Exception as e:
    print e

, . , . :

#!C:\Python27
import cx_Oracle

try:
    conn = cx_Oracle.connect("scott/tiger@oracle")
    curs = conn.cursor()
    curs.execute("SELECT dummy FROM sys.dual")
    print curs.fetchone()[0]
    curs.close()
    conn.close()
except Exception as e:
    print e

, , , .

-2

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