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IT130 Notes -- 5/13/09

Review Questions

1. Which C# method call causes a jump to a new webpage?
   Ans: Response.Redirect
    
2. The ASP.Net Code produces this output:

           Name  Gender  Age
   ====  =====   ===
   

   What is wrong?
    
   Ans: Since all whitespace within pre tags is preserved, any indentation spaces before the Literal control are also preserved.
    
3. Convert 9E_hex to decimal.
   Ans: 9E_hex = 16 * 9 + E = 128 + 14 = 142_dec
    
4. Convert 75_dec to hex.
   Ans: 75_dec = (75/16)(75%16) = (4)(11) = 4B_hex
    
5. Give the hex color codes for these colors:
    
   
   green = #00FF00 or #008000    yellow = #FFFF00    silver = #C0C0C0    pastel blue = #E0E0FF    brown = #503500


6. This code is supposed to find the total of all integers in an array. Find all the errors you can:

   int total;
   int a = {1, 2, 4, 9, 16, 25, 36};
   for(i = 1; i <= a.Length; i++);
   {
       total =+ a(i);
   }
   

   Ans:
   1. total should be initialized to 0.
   2. int a should be declared as int[ ] a.
   3. The for loop should go from 0 to a.Length - 1 instead of 1 to a.Length.
   4. =+ should be +=.
   5. a(i) should be a[i].
   
   
7. Convert the textfile persons.txt into an Access 97 database.
    
   Ans: See the document Importing a Textfile into Access
    
8. You are given the database table Persons with columns FirstName (class string), Gender (class string), and Age (class int). Write SQL statements to do the following:
    
1. Show all the names in the table.
   Ans: SELECT * FROM Persons;
    
2. Show the ages of everyone named Fred.
   Ans: SELECT Age FROM Persons WHERE Name='Fred';
    
3. Show the names of all women.
   Ans: SELECT Name FROM Persons WHERE Gender='F';
    
4. Show the ages of all men over 21.
   Ans: SELECT Age FROM Persons WHERE Gender='M' And Age>21;
    
5. Show the names of all men less than 25 and the names of all women less than 21.
   Ans: SELECT Age FROM Persons WHERE (Gender='M' And Age>25) Or (Gender='F' And Age>21);

Database Examples

• Use MS-Access to convert the CSV file from Project 5 into an Access 97 database.
   
• The OleDbConnection object provides a connection to the database.
   
• The OleDbDataAdapter object which populates a disconnected DataSet with data and performs updates on that data. The DataSet is represented using XML.
   
• The OleDbCommand object is used to execute an SQL command. It is used by the OleDataAdapter to determine which data from the database should be transfered to the DataSet.
   
• The OleDbDataReader object which provides a forward-only, read only, connected recordset.
   
• Here is a diagram of the ADO.Net Architecture.
   
• Here are the names of some data objects found in System.Data for various other providers.
   
• Look at these examples:
   
  
  54 (grocery-display3.aspx)
   
  55 (grocery-display4.aspx)