Using Python With Oracle Database 1. Purpose. This tutorial shows you how to use Python with Oracle Database 1. For more tutorials, visit the following Oracle By Examples articles: Developing a Python Web Application with Oracle Database 1. Using Python with Oracle Database 1. Time to Complete.

Approximately 1 hour. Overview. Python is a popular general purpose dynamic scripting language. With the rise of Frameworks, Python is also becoming common for Web application development. Adobe Font Folio 11 Download there. If you want to use Python and an Oracle database, this tutorial helps you get started by giving examples.

If you are new to Python review the Appendix: Python Primer to gain an understanding of the language. Prerequisites. For this Hands On Session, the following has already been installed for you: Oracle Database 1. R2, with a user . The example tables in this schema are from Oracle's Human Resources or . Many inbuilt and third party modules can be included in this way in Python scripts.

The connect() method is passed the username . In this case, Oracle's Easy Connect connection string syntax is used. It consists of the IP of your machine and the DB service name . Any connections not explicitly closed will be automatically released when the script ends.

Open Source Software in Python Open Source Aspect-Oriented Frameworks in Python. Aspects.py - aspects.py library provides means to intercept function calls. CGI - Dynamic Web Pages¶ CGI stands for Common Gateway Interface. This interface is used by web servers to process information requests supplied by a browser.

In a command line terminal run: python connect. If the connection succeeds, the version number is printed: An exception is thrown if the connection fails. Indentation is used in Python to indicate the code structure. There are no statement terminators unlike many other languages and there are no begin/end keywords or braces to indicate blocks of code. Open connect. py in an editor.

Indent the print statement by two spaces ad save the file. Here the Python interpreter is not expecting a new code block level after the connect() call so it warns about the different indentation. In other cases such as in 'if' and loop blocks (shown later), take care that all statements in each block are equally indented.

If you are copying and pasting from this lab, check the pasted indentation is correct before running each example. Python treats everything as an object. The last element of the list is ver. A list slice is created by ver. This returns the elements starting at position 1 and up to, but not including, elements from position 4. Python lists have methods and can also be manipulated with operators.

Change connect. py to. The remove(. The first print and if are at the same level of indentation because they are both inside the loop. Re- run the script in the command line terminal: python connect. The loop prints and tests each value from the list in turn. Using Database Resident Connection Pooling. Database Resident Connection Pooling is a new feature of Oracle Database 1.

It is useful for short lived scripts such as typically used by web applications. It allows the number of connections to be scaled as web site usage grows. It allows multiple Apache processes on multiple machines to share a small pool of database server processes. Without DRCP, a Python connection must start and terminate a server process. Below left is diagram of nonpooling. Every script has its own database server proces. Scripts not doing any database work still hold onto a connection until the connection is closed and the server is terminated.

Below right is a diagram with DRCP. Scripts can use database servers from a pool of servers and return them when no longer needed. Batch scripts doing long running jobs should generally use non- pooled connections. This tutorial shows how DRCP can be used by new or existing applications without writing or changing any application logic. Perform the following steps: Review the code as follows, which is contained in the connect. A Connection Class . Session information (such as the default date format) might be retained between connection calls, giving performance benefits. Emilie Simon Desert Free Download on this page.

Session information will be discarded if a pooled server is later reused by an application with a different connection class name. Applications that should never share session information should use a different connection class and/or use ATTR. This reduces overall scalability but prevents applications mis- using session information. Run connect. There are a number of functions you can use to query an Oracle database, but the basics of querying are always the same: 1. Parse the statement for execution.

Bind data values (optional). Execute the statement. Fetch the results from the database. To create a simple query, and display the results, perform the following steps. Review the code as follows that is contained in the query. HOME directory. Perform the following steps.

Review the code as follows that is contained in the query. When called multiple time, consecutive rows are returned: Run the script in a terminal window. Here the num. Rows parameter specifices that three rows should be returned. Run the script in a terminal window. The output is a list (Python's name for an array) of tuples. Each tuple contains the data for one row.

The list can be manipulated in the any Python manner. The choice of which fetch method to use will depend on how you want to process the returned data. Improve Query Performance. This section demonstrates a way to improve query performance by increasing the number of rows returned in each batch from Oracle to the Python program. Perform the following steps: First, create a table with a large number of rows. Review the following query. The arraysize is set to 1.

This causes batches of 1. Python. This reduces the number of . The fetchone(), fetchmany() and even fetchall() methods will read from the cache before requesting more data from the database. From a terminal window, run: python query. In general, larger array sizes improve performance. Depending how fast your system is, you may need to use different arraysizes than those given here to see a meaningful time difference. There is a time/space tradeoff for increasing the arraysize.

Larger arraysizes will require more memory in Python for buffering the records. Using Bind Variables. Bind variables enable you to re- execute statements with new values, without the overhead of reparsing the statement. Bind variables improve code reusability, and can reduce the risk of SQL Injection attacks. To use bind variables in this example, perform the following steps.. Review the code as follows that is contained in the bind. The statement is only prepared once but executed twice with different values for the WHERE clause.

The special symbol 'None' is used in place of the statement text argument to execute() because the prepare() method has already set the statement. The second argument to the execute() call is a Python Dictionary. In the first execute call, this associative array has the value 2. The second execute uses the value 1. From a terminal window, run. The setinputsizes() call describes the columns.

The first column is integral. The second column has a maximum of 2. The executemany() call inserts all seven rows. The commit call is commented out, and does not execute.

The final part of the script queries the results back and displays them as a list of tuples. From a terminal window, run: python bind. When the changed data is committed to the database, it is then available to other users and sessions. This is a database transaction. Perform the following steps. Edit the script used in the previous section bind.

Doing your own transaction control has performance and data- integrity benefits. Using PL/SQL Stored Functions and Procedures.

PL/SQL is Oracle's procedural language extension to SQL. PL/SQL procedures and functions are stored and run in the database.

Using PL/SQL lets all database applications reuse logic, no matter how the application accesses the database. Many data- related operations can be performed in PL/SQL faster than extracting the data into a program (for example, Python) and then processing it. Oracle also supports Java stored procedures. In this tutorial, you will create a PL/SQL stored function and procedure and call them in Python scripts. Perform the following steps...