Write a console application that populates the draws table using a lottery file。 Write a console application that dumps the contents of the draws table as a lottery file。 2。 Create a console application that accepts as mand…line arguments a winner and the date of the draw。 Your console application must account for doubles and populate both the persons and winners tables。 …………………………………………………………Page 416…………………………………………………………… …………………………………………………………Page 417…………………………………………………………… C H A P T E R 1 5 ■ ■ ■ Learning About LINQ In the previous chapter； you learned about how to access a database using the traditional ADO technologies。 When you make ADO requests； you are making SQL calls and organizing the result set data using SQL。 Language Integrated Query （LINQ） is a technology that lets you organize your results in a consistent manner； regardless of the underlying source of the data。 Why yet another technology to query information？ The answer is related to XML。 XML is a technology used to represent information in a hierarchical manner。 You saw an example of XML in Chapter 12。 XML has solved many problems in an elegant and understand able manner。 One of the solutions proposed by XML is the ability to reference information in an XML structure with XPath； which is a way of referencing an object structure using a set of filters。 Using XPath； you can find any node； and the filters can include the presence of depen dent elements； which is not easily possible in other technologies。 Put simply； XPath and XML are very powerful techniques used to find information。 You can consider XML and XPath as inspiration for LINQ。 Where LINQ and XML XPath deviate is that LINQ can be used to query Visual Basic collection objects； XML documents； and relational databases。 Think of LINQ as a general mechanism used to search a collection of information。 The focus of this chapter will be to explain the mechanics of LINQ； and demon strate how to write queries and use the methods associated with the LINQ library。 Finding the Frequency of Winning Numbers The lottery application we’ve been working with in previous chapters collects information about lottery drawings to predict the next set of winning lottery numbers。 The idea is to find patterns。 Again； the reality is that lottery drawings are random； so even if you could identify patterns； that wouldn’t mean you could predict winning numbers。 However； what is interesting about this problem is that you can use LINQ to slice and dice the data。 LINQ lets you keep the data as objects； and to perform SQLand XPath…like operations； as you’ll see in this chapter。 In Chapter 10； you saw a streaming architecture； where a console application read in text data and spat out text data。 You also saw examples of text…to…binary and binary…to…text conver sions。 The application in this chapter （in the FrequencyProcessor project） will read in text； process the data； and then generate text describing the frequency of lottery numbers。 Thus； we need to use the text…to…text interface； which was defined in Chapter 10 as follows： 395 …………………………………………………………Page 418…………………………………………………………… 396 CH AP T E R 1 5 ■ L E A R N I N G A B OU T L I N Q Public Interface IProcessor Function Process（ByVal input As String） As String End Interface The input is a text stream that looks like this： 2006。03。11 3 7 15 28 30 38 44 2006。03。15 10 18 30 34 41 43 5 2006。03。18 3 11 12 16 20 40 9 2006。03。22 2 3 7 13 42 43 41 2006。03。25 3 10 36 40 43 44 35 2006。03。29 3 4 8 16 34 39 45 If you want to find the frequency of the individual numbers； you could parse each individual number； and then increment the count of the individual number as an array； like this： Dim frequency As Integer = 0 Dim splitUpText（） As String = lineOfText。Split（New Char（） ｛〃 〃c｝） frequency（Integer。Parse（splitUpText（0））） ＋= 1 frequency（Integer。Parse（splitUpText（1））） ＋= 1 。 。 。 The split line of text contains the list of numbers； separated by spaces； which is then converted to a series of numbers； each of which is used as an index for the frequency。 The solution is fast and works； but it has a big problem： it is not extendable。 The solution solves a single problem and only a single problem。 For example； let’s say that you want to figure out other statistical information； such as which numeric binations occur most often。 Using the previous solution； that would require reparsing the text stream again。 That is an expensive and tedious solution。 The better solution would be to convert the stream into a series of objects that could be processed。 However； the problem at hand is calculating the frequency of individual numbers。 So why exert the extra effort if the solution that solves the single problem works？ Writing good code means solving problems using a generic but specific approach。 You want to write specific code so that you do not get bogged down in thinking about details in the future； and you want to write generic code so that any future requirement does not cause you to pletely rewrite the old application。 Knowing when to write specific code and when to write generic code is really a matter of experience—the only way to learn is to write code。 Extending the Lottery…Prediction System In Chapter 10； the IPr