How to Create and Use of Iterators, yield: CSharp Programming

Programmer often use some type of iterators that are used to iterate steps in the programming language. An iterator often use yield keyword to return individual element, this is possible only if it have the current location in the cache.

C# Programming uses these iterators to execute some steps continuously like returning a value continuously from a method. Following program is creating an iterator in c# language.

public Form()
{
InitializeComponent();
foreach (int number in SomeNumbers())
{
string str = number.ToString() + " ";
}
}
public static System.Collections.IEnumerable SomeNumbers()
{
yield return 1;
yield return 2;
yield return 3;
}

Yield keyword keeps the current position of the currently executing statement, so that the iteration can be performed.

Here Foreach keyword is used for looping statements in c# programming language, but it is also used as iterators. Each time when the SomeNumbers() method is called in this loop, the yield keyword will return the specified number and will back to the current position.

That is why the resulting string in str variable will be "1 2 3". There may be many ways to creating iterators like:

Using Collection Class: As the well-known class collection is used to automatically called GetEnumerator method which returns IEnumerable type of data. The same process can be easily implemented using this collection class.

Using Generic List: As GetEnumerator method returns an array of specified elements. Generic method is inherited from IEnumerable interface. Using this method iterators can easily be implemented as in above program.

Create Stored Procedure for accessing data from database in ASP.NET, Example

In my previous post we have discussed about how to design Department table for shopping cart. Now, we will learn, How to create stored procedure for retrieving  information from database table. You need to create the GetDepartments stored procedure, which returns department information from the Department table. This stored procedure is part of the data tier and will be accessed from the business tier. The final goal is to have this data displayed in the user control.

The SQL code that retrieves the necessary data and that you need to save to the database as the GetDepartments stored procedure is the following:

Select DepartmentID, Name, Description From Department

This command returns all the department information

Note: unless you have a specific reason to do so, never ask for all columns (using the * wildcard) when you only need a part of them. This generate more traffic and stress on the database server then necessary and slows down performance. Moreover, even if you do need to ask for all columns in the table, it's safer to mention them explicitly to protect your application in case the number of order of columns changes in future.

Saving the Query As a Stored Procedure

As with data tables, after you know the structure, implementing the stored procedure is a piece of cake. Now that you know the SQL code, the tools will help you save the query as a stored procedure easily.

The Syntax for creating a stored procedure that has no input or output parameters is as follows:

CREATE PROCEDURE <procedure name>
AS
<stored procedure code>

if the procedure already exists and you just want to update its code, use alter PROCEDURE instead of above. Stored procedures can have input or output parameters. Because GetDepartments doesn't have any parameters, you don't have to bother about them right now.

Lets take a simple example of writing the Stored Procedure

Step-1: Make sure the data connection to the database is expanded and selected in server explorer. Choose data->Add New--> Stored Procedure. Alternatively, you can right-click the Stored Procedure node in server explorer and select Add New Stored Procedure.

Step-2: Replace the default text with GetDepartment's stored procedure

CREATE PROCEDURE GetDepartments 

AS
SELECT DepartmentID, Name, Description
From Department

Step-3: Press Ctrl+S to save the stored procedure. Unlike with the tables, you won't be asked for a name because the database already knows that you're talking about the GetDepartment's stored procedure

Note: Saving the Stored Procedure actually executes the SQL code you entered, which creates the stored procedure in the database, after saving the procedure, the CREATE keyword becomes ALTER, which is the SQL command that changes the code of an existing procedure.

Step-4: Now test your first stored procedure to see that it's actually working. Navigate to the GetDepartments stored procedure node in server explorer and select execute.

Step-5: After running the stored procedure, you can see the results in the output window.

How to Create a GUI application Showing Details in I-Card Format, NetBeans: Java Programming

NetBeans provides a simple and easy way to create a new project and input some information in sql programming. The article will let the programmer do the same thing.

• Start NetBeans and create a new project and add four labels and four textfields from the palette tab as explained in earlier article.

• Set following font properties for all the labels and textfields.
  Type: Comic Sans MS (you may choose any other font if you wish)
  Style: Bold
  Size: 12

• Adjust the placement of Heading, whose properties you set just now, by dragging it, so that it appears in the middle horizontally. Set name property of the labels respectively:
  jLabel1   to    titlelabel1
  jLabel2   to    firstNameLabel
  jLabel3   to    lastNameLabel
  jLabel4    to   classLabel
  jTextField1    to        firstNameTextField
  jTextField2    to        lastNameTextField
  jTextField3    to        classTextField
  jTextField4    to        sectionTextField

• Set text property for these labels as given below:
  titleLabel1  to  Title(Mr/Ms)
  firstnameLabel  to  First Name
  lastnameLabel    to    Last Name
  classLabel  to  Class

• Also set the text property of each of null string i.e. “ “ and resize them as per the screenshot. Now your frame should look like the one shown in below

• Add a Button control by dragging it from Palette to frame. Name it as okButton. Set its text property to Generate and its font remain as is.

Before you add text area to frame, you may need to increase the size of the frame. For this drag the boundary of the frame in desired direction to get its desired size.

• Just as you added other controls, add a text field control to your frame and give it a size according to I-Card. Name it as repTextArea. To name the text area field, you need to click the jScroolPane control in inspector window. A Scroll pane automatically gets added to your frame when you add a text area.

• Adding Functionality to Frame
  Now double click on the boundary of the push button i.e., the okButton in design space. The code editor window will get opened. In it, without touching the cursor, simply type the following code. For now you won’t understand it. But it will be clear to you later when we’ll be talking about java concepts.

When you use getText() with a control’s name followed by a dot(.). It returns the text stored in the control. So the code will give the text stored in the control whose name is titlenameField.

Now save your work by pressing Ctrl + S and press F6 to run your project. You may also click Run icon on the toolbar. See your application run. After entering details in text fields, click on Generate. Wow, isn’t it similar to one shown in screenshot?

Computer Programming: Department table for shopping cart in ASP.NET, Example

In computer Programming, database is the important concept of any one project. In this article we will learn the first step of e-commerce project, which is database (table) design. Follow the steps for designing department table.

Step-1: In server explorer, expand the database node, right-click the Tables node, and select Add New Table from the context menu.
Step-2: A form appears where you can add columns to the new table. Using this form, add three columns, with the properties described in table.

Note : You set a column to be the primary key by right-clicking it and clicking the Set Primary Key item from the context menu. You set a column to be an identity column by expanding the Identity Specification item from its Column Properties window, and setting the (Is Identity) node to yes. You can also access the identity increment and Identity Seed vales, if you should ever want to use values other than the defaults.

Step-3: After adding these fields, the form should look like.

Step-4: Now that everything is in place, you need to save the newly created table. Press Ctrl+S, write table name in appeared popup.

Step-5: After creating the table in the database, you can open it to add some data. To open the Department table for editing, right-click it in Server explorer and select Show Table Data from the context menu.
(Alternatively, you can choose Database->Show Table Data after selecting the table in server explorer)

Using the integrated editor, you can start adding rows. Because DepartmentID is an identity column, you cannot manually edit its data--SQL Server automatically fills this field, depending on the identity seed and identity increment values that you specified when creating the table.

Step-6: Add two departments.

Computer Programming:inline code or Code render block in ASP.NET, Example

Code render blocks define the inline code or inline expressions that are executed when a web page is rendered. The inline code is then executed by the server and the output is displayed on the client browser that requested for the page. The code render blocks are capable of displaying information on the client browser without customarily calling the write method. The code render blocks are represented on a page by the <% %> symbols. The code present inside these symbols is executed in the top-down manner. Now, let's put the concept of code render bock into use by creating an application, CodeRenderBlock. This application use a code render block to implement a loop used for changing the text size.

Lets take a simple example, change font size in asp.net using loop

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    <title>Change Font size inline code model</title>

</head>

<body>

    <form id="form1" runat="server">

    <div>

    <% for(int i=0;i<6;i++)

           

       { %>

       <font size="<%=i %>" >Hello World ! </font><br />

       <% } %>

    </div>

    </form>

</body>

</html>

Code generate following output

How to Create a GUI application displaying a String in NetBeans: Java Programming

NetBeans provides a simple and easy way to create a new project and display a string in sql programming. The article will let the programmer do the same thing.

• Start NetBeans and create a new project as explained in earlier article. You can change the name of the project otherwise it will automatically set. Add new frame in the same way discussed earlier. By default the name of frame will be NewJFrame.

• Draw a Label control on your frame by dragging it from the Swing Controls section of the Palette.

• To change the name of this Label, right click on its default name, which is JLabel1, under the Inspector window and select Change Variable Name……. command as shown in the image.

• Keeping the label control selected in its design space, do in the Properties window :
  
  Click the ellipsis button of the font property and selected font as:
  Type: Comic Sans MS (you may choose any other font if you wish)
  Style: Bold
  Size: 18

• Type "Computer Programming" (without quotes) in the text property's box or by clicking at its ellipsis button. Now your project window will appear something like:

• Adjust the placement of the title label, whose properties you set just now, by dragging it, so that it appears in the middle horizontally.

• On the same lines, add one more Label to your frame by dragging it from the Palette. Set its font as per you wish. Select the colour of the font by clicking the ellipsis of the foreground property in Properties window. Now specify its text as: "A Complete Programming Blog with SQL, JAVA, C, C#".

• Adjust its placement as per you wishes. Now your project window will appear somewhat like:

• Right click on the jFrame you have created and click on Run File, it will show the frame which will look like:

In this workshop you have learnt about following properties of jLabel control.

• font: The property used to specify the display font, style and size for the display text of the jlabel. Font is selected by clicking ellipsis button in font property's box.
• foreground: The property used to specify foreground color of jLabel, you can select desired colors by clicking of the foreground property.
• text: The property used to specify the display text. You can either type the display text directly in front of text property’s name click to type it in a separate box. Small texts you can type directly, for big texts, its better them separately.

Ranking Functions to Generate Sequential Numbers in Sql Server: SQL Programming

In SQL Programming, ranking functions are used to operate with numeric values. Programmer can easily perform all type of ranking functions to generate sequential numbers for each row based on specific criteria.

You can use ranking functions to generate sequential numbers for each row or to give a rank based on specific criteria. For example, in a manufacturing organization, the management wants to rank the employees based on their salary. To rank the employees, you can use the rank function.

Ranking function return a ranking value for each row. However, based on the criteria, more than one row can get the same rank. You can use the following functions to rank the records:

• row_number
• rank
• dense_rank

All these functions make use of the OVER clause. This clause determines the ascending or descending sequence in which rows are assigned a rank. The row_number function returns the sequential numbers, starting at 1, for the rows in a result set based on a column.

For example, the following SQL query displays the sequential number on a column by using the row_number function:

SELECT BusinessEntityID, Rate, row_number ( ) OVER (ORDER BY Rate desc) AS RANK 
FROM HumanResources.EmployeePayHistory

The following figure displays the output of the preceding query.

dense_rank Function

The dense_rank( ) function is used where consecutive ranking values need to be given based on a specified criteria. It performs the same ranking task as the rank function, but provides consecutive ranking values to an output.

For example, you want to rank the products based on the sales done for that product during a year. If two products A and B have same sale values, both will be assigned a common rank. The next product in the order of sales values, both will be assigned a common rank. The next product in the order of sales values would be assigned the next rank value.

If in the preceding example of the rank function, you need to give the same rank to the employees with the same salary rate and the consecutive rank to the next one. You need to write the following query:

SELECT BusinessEntityID, Rate, dense_rank( ) OVER (ORDER BY Rate desc) AS rank 
FROM HumanResources.EmployeePayHistory