Using the Python Database APIs

First, some history about Python and relational databases. Python’s support for relational databases started out with ad hoc solutions, with one solution written to interface with each particular database, such as Oracle. Each database module created its own API, which was highly specific to that database because each database vendor evolved its own API based on its own needs. This is hard to support, because coding for one database and trying to move it to the other gives a programmer severe heartburn, as everything needs to be completely rewritten and retested.

Over the years, though, Python has matured to support a common database, or DB, API, that’s called the DB API. Specific modules enable your Python scripts to communicate with different databases, such as DB/2, PostgreSQL, and so on. All of these modules, however, support the common API, making your job a lot easier when you write scripts to access databases. This section covers this common DB API.

WordPress Database Class

WordPress features an object class with method functions for working with the database directly. This database class is called wpdb and is located in wp-includes/wp-db.php. Any time you are querying the WordPress database in PHP code you should use the wpdb class. The main reason for using this class is to allow WordPress to execute your queries in the safest way possible.

Simple Database Queries

When using the wpdb class, you must first define $wpdb as a global variable before it will be available for use. To do so just drop this line of code directly preceding any $wpdb function call:

global $wpdb;

Chapter 56: LINQ to SQL

What’s In This Chapter?

• Working with LINQ to SQL using Visual Studio 2010

• Mapping LINQ to SQL objects to database entities

• Building LINQ to SQL operations without the O/R Designer

• Using the O/R Designer with custom objects

• Querying the SQL Server database using LINQ

• Stored procedures and LINQ to SQL

You will probably find the .NET Language Integrated Query Framework (LINQ) in C# 2010 to be one of the more exciting features the language has to offer. Basically, what LINQ provides is a lightweight façade over programmatic data integration. This is such a big deal because data is king.

Pretty much every application deals with data in some manner, whether that data comes from memory (in-memory data), databases, XML files, text files, or something else. Many developers find it very difficult to move from the strongly typed object-oriented world of C# to the data tier where objects are second-class citizens. The transition from one world to the next was a kludge at best and was full of error-prone actions.

In C#, programming with objects means a wonderful, strongly typed ability to work with code. You can navigate very easily through the namespaces, work with a debugger in the Visual Studio IDE, and more. However, when you have to access data, you will notice that things are dramatically different.