Automate Database Deployment with Python By Michael McLaughlin Python cx_Oracle Tutorial cx_Oracle Documentation

Objectives Introduce Python Learn how to install cx_Oracle Learn how to connect to Oracle Learn how to run static SQL statements Learn how to run dynamic SQL statements Learn how to call PL/SQL store programs

Introduce Python

Python? A robust high-level programming language: Gets complex things done quickly Automate system and data integration tasks Solve complex analytical problems

Install cx_Oracle Driver

The cx_Oracle Driver Conforms to the Python DB API 2.0 Requires Oracle Client Installation Not presently in standard Linux repos You can download from here: https://pypi.python.org/pypi/cx_Oracle

Installing cx_Oracle Driver Things you need to know first: Ships for Linux/Unix in RPM file Ships for Windows in MS Windows Installer file Available for Python 2.6/2.7 on Linux/Unix Available for Python 2.6/2.7/3.4-3.6 on Windows Requires local Oracle Instant Client insall Supports platforms: Linux, Unix, Mac OS X, and Windows

Installation Steps (as root) Check your Python version with: # python -V Check for Oracle Client installation: # rpm –qa oracle-instantclient11-2-basic # yum install -y /tmp/oracle-instantclient* Install cx_Oracle Driver: # yum install -y cx_Oracle-5*

Verify cx_Oracle Installation Connect to the Python IDLE environment Type in the following commands: >>> import cx_Oracle >>> db = cx_Oracle.connect("student/student@xe") >>> print db.version Returns the following for Oracle 11g XE: 11.2.0.2.0

Connect to Oracle

Implement a connect.py script #!/usr/bin/python # Import the Oracle library. import cx_Oracle, sys try: # Create a connection. db = cx_Oracle.connect("student/student@xe") # Print a message. print "Connected to the Oracle " + db.version + " database." except cx_Oracle.DatabaseError, e: error, = e.args print >> sys.stderr, "Oracle-Error-Code:", error.code print >> sys.stderr, "Oracle-Error-Message:", error.message finally # Close connection. db.close();

Run a static SQL Statement

Implement a static query #!/usr/bin/python ... try: # Create a connection. db = cx_Oracle.connect("student/student@xe") # Create a cursor. cursor = db.cursor() # Execute a query. cursor.execute("SELECT 'Hello world!' FROM dual") # Read the contents of the cursor. for row in cursor: print (row[0]) ... finally: # Close cursor and connection. cursor.close() db.close()

Returning rows from a cursor #!/usr/bin/python ... # Execute a query. cursor.execute("SELECT item_title " + ", item_rating " + "FROM item " + "WHERE item_type = ” " (SELECT common_lookup_id " + " FROM common_lookup " + " WHERE common_lookup_type = 'DVD_WIDE_SCREEN')") # Read the contents of the cursor. for row in cursor: print (row[0], row[1]) ...

Run a dynamic SQL Statement

Binding a value in a cursor The local variable. #!/usr/bin/python ... sRate = 'PG-13' ... # Define a dynamic statment. stmt = "SELECT item_title, item_rating " + \ "FROM item WHERE item_rating = :rating” # Create a cursor. cursor = db.cursor() # Execute a statement with a bind variable. cursor.execute(stmt, rating = sRate) # Read the contents of the cursor. for row in cursor: print (row[0], row[1]) ... The bind variable. Name and value pair assignment.

Binding two values in a cursor The list of local variables. #!/usr/bin/python ... # Define a list. dvd = ('DVD_FULL_SCREEN','DVD_WIDE_SCREEN')| ... stmt = "SELECT common_lookup_id" + "\n" + \ "FROM common_lookup" + "\n" + \ "WHERE common_lookup_table = 'ITEM'" + "\n" + \ "AND common_lookup_column = 'ITEM_TYPE'" + "\n" + \ "AND common_lookup_type IN (:x,:y)” # Parse the statement by replacing line returns with a single # whitespace, replacing multiple whitespaces with single spaces. stmt = re.sub('\s+',' ',stmt.replace('\n',' ').replace('\r','')) # Declare a dynamic statement with a sequence. cursor.execute(stmt, x = dvd[0], y = dvd[1]) ... The bind variables. Name and value pair assignment.

Binding a dynamic dictionary A tuple used to name dictionary names, or the names of name-value pairs. #!/usr/bin/python ... # Define an alphabetic indexing tuple. ind = tuple('abcdefghijklmnopqrstuvwxyz') # Define a parameter list and empty target list. typ = ('DVD_FULL_SCREEN','DVD_WIDE_SCREEN','BLU-RAY') mat = {} ... A dynamic list of variables that need to bound to a dynamic SQL statement Declaring an empty dictionary.

Binding a dynamic dictionary Beginning of list of values. ... # Define a dynamic query. stmt = "SELECT common_lookup_id" + "\n" + \ ... "AND common_lookup_column = 'ITEM_TYPE'" + "\n" + \ "AND common_lookup_type IN (" # Build dictionary and append dynamic bind list to statement. for j, e in enumerate(typ): mat[str(ind[j])] = typ[j] if j == len(typ) - 1: stmt = stmt + ":" + str(ind[j]) else: stmt = stmt + ":" + str(ind[j]) + ", " # Close lookup value set. stmt = stmt + ")" + "\n" \ "ORDER BY 1” ... Logic to build list of bind variables and dynamic dictionary. Append closing parenthesis of list.

Dynamic statement and dictionary Generated dynamic statement: AND    common_lookup_column = 'ITEM_TYPE' AND    common_lookup_type IN (:a, :b, :c) ORDER BY 1 Parse the query for line returns: stmt = re.sub('\s+',' ',stmt.replace('\n',' ').replace('\r','')) Generated mat dictionary: {'a': 'DVD_FULL_SCREEN', 'c': 'BLU-RAY', 'b': 'DVD_WIDE_SCREEN'} Call the query with a dictionary:   cursor.execute(stmt, mat)

Assign local variables to bind targets. Binding a transaction ... # Declare variables. sItemTitle = 'Star Trek Beyond’ sItemSubtitle = 'Extended Edition' ... # Execute a query. stmt = "UPDATE item"                           + "\n" + \      "SET    item_subtitle = :bItemSubtitle" + "\n" + \      "WHERE  item_title = :bItemTitle" ... # Declare a dynamic statement. cursor.execute(stmt, bItemTitle = sItemTitle                        , bItemSubtitle = sItemSubtitle ) # Commit the inserted value. db.commit() ... Assign local variables to bind targets. Commit change.

Transaction Control You start a transaction like: # Set a starting transaction point. db.begin() Commit the write in the try-block: db.commit() Rollback in the except block with an error: db.rollback()

Call PL/SQL stored programs

Calling a procedure First call parameter is the name of the procedure. ... # Create a connection. db = cx_Oracle.connect("student/student@xe") # Create a cursor. cursor = db.cursor() # Call a stored procedure. cursor.callproc( 'insert_bill_detail' \ , ( sBillNumber \ , sBillText \ , sDetailNumber \ , sDetailText )) ... First call parameter is the name of the procedure. Second call parameter is the list of actual parameters.

Calling a procedure with list A parameter list. ... # Create a sequence for a procedure call. param = (sBillNumber, sBillText, sDetailNumber, sDetailText) try: # Create a connection. db = cx_Oracle.connect("student/student@xe” # Create a cursor. cursor = db.cursor() # Call a stored procedure. cursor.callproc( 'insert_bill_detail', param) ... Call parameters bundled in a list.

Calling a function with list ... # Create a sequence for a procedure call. param = (sBillNumber, sBillText, sDetailNumber, sDetailText) try: # Create a connection. db = cx_Oracle.connect("student/student@xe") # Create a cursor. cursor = db.cursor() # Call a stored procedure. fRetVal = cursor.callfunc( 'insert_bill_detail_func', cx_Oracle.NUMBER, param) # Check for successful function call or failure number. if fRetVal == 0: print "Success” else: print "Failure [" + str(int(fRetVal)) + "]” ... Function return type. Capture a failure code from the function.

Review Introduce Python Learn how to install cx_Oracle Learn how to connect to Oracle Learn how to run static SQL statements Learn how to run dynamic SQL statements Learn how to call PL/SQL store programs

Questions & Answers