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Listings 7-5 through 7-12 show the CREATE TABLE commands for the seven case tables of this book. The constraints in these CREATE TABLE commands are meant to be self-explanatory, showing various examples of PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, and NOT NULL constraints.

IF OBJECT_ID('tempdb..#CachedPages') IS NOT NULL DROP TABLE #CachedPages; GO CREATE TABLE #CachedPages ( rownum INT NOT NULL PRIMARY KEY, orderid INT NOT NULL UNIQUE, orderdate DATETIME NOT NULL, custid INT NOT NULL, empid INT NOT NULL );

Figure 6-28. Selecting the parameters for your banner graphic When you click the OK button, the script will execute and generate the requested graphic. That s it! My logo generated as shown in Figure 6-29. Try a number of the logo scripts, and you will almost certainly find some graphic that appeals to you and fits the look of your web site. When you ve chosen the appropriate graphic, save it as a JPG or PNG file and store it in the \images folder of your template. The most important step is just ahead: creating the index file of your template.

The SQL queries you write must be sent somehow to the database engine for execution. As you learned in 2, you ll use PHP PDO to access the PostgreSQL server. Before writing the business tier code, you need to analyze and understand the possibilities for implementation. The important questions to answer before writing any code include the following: What strategy should you adopt for opening and closing database connections, when you need to execute an SQL query Which methods of PHP PDO should you use for executing database functions and returning the results How should you handle possible errors and integrate the error-handling solution with the error-handling code you wrote in 2 Let s have a look at each of these questions one by one, and then we ll start writing some code.

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For an example of creating an accessor and then calling the Execute method, see the section Retrieving Data as Objects Asynchronously later in this chapter. Creating and Using Mappers In some cases, you may need to create a custom parameter mapper to pass your parameters to the query that the accessor will execute. This typically occurs when you need to execute a SQL statement to work with a database system that does not support parameter resolution, or when a default mapping cannot be inferred due to a mismatch in the number or types of the parameters. The parameter mapper class must implement the IParameterMapper interface and contain a method named AssignParameters that takes a reference to the current Command instance and the array of parameters. The method simply needs to add the required parameters to the Command object s Parameters collection. More often, you will need to create a custom output mapper. To help you do this, the block provides a class called MapBuilder that you can use to create the set of mappings you require between the columns of the data set returned by the query and the properties of the objects you need. By default, the accessor will expect to generate a simple sequence of a single type of object (in our earlier example, this was a sequence of the Product class). However, you can use an accessor to return a more complex graph of objects if you wish. For example, you might execute a query that returns a series of Order objects and the related Order Lines objects for all of the selected orders. Simple output mapping cannot cope with this scenario, and neither can the MapBuilder class. In this case, you would create a result set mapper by implementing the IResultSetMapper interface. Your custom row set mapper must contain a method named MapSet that receives a reference to an object that implements the IDataReader interface. The method should read all of the data available through the data reader, processes it to create the sequence of objects you require, and return this sequence.

public static void CallbackWithoutNewingADelegateObject() { ThreadPool.QueueUserWorkItem( // The callback code can reference static members. obj =>Console.WriteLine(sm_name+ ": " + obj), 5); } }

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