Sampath's Blog

Maintain multiple Facebook accounts

2011-11-18T19:59:00.000-08:00

If you are having more than one Facebook accounts(or even one) and you can add this extension named "Quick Login for Facebook Accounts" to your Chrome browser. The extension is from the guys who have created the extension "Quick Login for Gmail" (my previous post). This is also pretty simple and cool.

More information can be found here;
Quick Login for Facebook Accounts

One click does the magic. :)

Chrome Extension to maintain multiple gmail accounts

2011-11-18T19:41:00.000-08:00

It is little harder to keep remember passwords of our Gmail accounts all the time. Recently, I have found the following chrome browser extension "Quick Login for Google Accounts" which solves the above problem. No more worries about the password maintenance. It is also secure.

More details about the Quick Login chrome extension;
Quick Login for Google Accounts

Really good and simple extension. Thanks to the guys who created this.

Simple LINQ - SQL Connecting Program in C#

2010-01-25T18:53:00.000-08:00

LINQ - Language Integrated Query.It provides the Querying ability to the database and also doing the DML operations such as insert, update and delete.for more about LINQ, have a look at http://msdn.microsoft.com/en-us/library/bb308959.aspx

There are infinite pages are available to describe the Linq, its functionality, and design. But for a beginner, let us go with creating a simple application using Linq and playing with database. Before writing the program, we need to know the following basic things.
1. DataContext
This is a Layer or cache kind of stuff which interacts between the database and application. The application uses the datacontext to manipulate data with the database.
2. dbml - Database Markup Language
Linq to SQL class is known as dbml. The dbml maintains the tables and linkings.

Now we start with creating simple program. The aim of the program is to display the Northwind customers data whose names are starting with "a" in a datagrid.
Step 1: Create new C# windows project in VS2008.
Step 2: Import SqlClient/Oledb classes for database usage.
Step 3: Create dbml file. Right click Project and add New Item. Choose the "LINQ to SQL Classes" from the templates section. Name it as you like, here let us name it as "SampleNwnd". The extension would be ".dbml".
The dbml file will be opened with empty designer window saying that "Create data classes by dragging items from "Server Explorer" or "Toolbox" onto this design surface.
Step 4: Click the "Server Explorer" link and create a data connection. Right Click "Data connection" and click "Add Connection". This will open up the "Add Connection" window which contains the SQL Server credentials, database and authentication. Choose the appropriate settings and click "Ok" to complete the connection.

Once the connection has been added, the database tables, schema, procedures, views everthing will be shown.
Just drag and drop the Tables, Views to the dbml design window. To create the linking/association between the selected tables, Right click dbml screen ==> Add ==> Association. The Association editor will be shown. From there we can bind the master and child table relationship.

The next thing is coding part. We need to use the dbml in the coding. We may play with database activities such as view, insert, update and delete. Here let us display the list of customers in Northwind database whose names are starting in "a".
Here is the simple code;

private void button1_Click(object sender, EventArgs e)
{
try
{
SqlConnection conn = new SqlConnection("connection string");
conn.Open();
SampleNwndDataContext nwnd = new SampleNwndDataContext(conn);
var customers = from cust in nwnd.Customers
where cust.First_Name.StartsWith("a")
select cust;
dataGridView1.DataSource = customers;
conn.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}

The above code will display the data in a gridview. Here, "SampleNwndDataContext" is the data context class which we have added in the project. The tables which are added in the dbml file, those will be accessible inside the program. There are enormous options in LINQ to explore. But I believe this will be a starting point on that.
For more sample programs on LINQ, have a look at http://msdn.microsoft.com/en-us/vcsharp/aa336746.aspx

Character casing in Asp.net

2009-12-26T09:52:00.000-08:00

We might used the "Charactercasing" property of Textbox in C# windows applications. This is used to get the input values as upper or lower case without doing the separate coding. But in web applications,this property is not available directly. But we need to achieve this functionality using CSS.

In CSS, we need to use the "text-transform" property to make the input text as upper, lower or initcaps.

Here is the CSS sample:

.makeuppercase

{

text-transform:uppercase;

}

.makelowercase

{

text-transform:lowercase;

}

.makeinitcaps

{

text-transform:capitalize;

}

Need to assign the style name to TextBox "CssClass" property as;

TextBox1.CssClass = "makeuppercase"

The above code will make the input values to upper case while entering the values.

XML Documentation comments

2009-12-26T02:05:00.000-08:00

When we are doing the coding, we need to use our own functions/methods to do a certain task. But while writing the function we may missed out the function details like why the function has been written.

So whenever writing a function, if we use the documentation comments standard, it will help in the future whoever uses the function.

Here is syntax;

///

/// documentation block

///

Here is the simple function defined in C# IDE;

documentation comments added here;

Intellisense is displaying the documentation comments.

Storing Images in MySQL database

2009-12-18T22:37:00.000-08:00

We may need to store the images in the database. It is easy and pretty simple.

The basic idea is;

1) The images are stored in database as bytes. In MySQL database we need to create a field/column of type "Blob".

2) Need to use FileStream and BinaryReader objects to convert images into bytes.

Here is the C# code, to do the task

Table schema:

C# code:

MySqlConnection mcon = null;

MySqlCommand cmd = null;

FileStream fsObj = null;

BinaryReader binRdr = null;

try

{

//converting image to bytes

fsObj = File.OpenRead(pictureBox1.ImageLocation);

byte[] imgContent = new byte[fsObj.Length];

binRdr = new BinaryReader(fsObj);

imgContent = binRdr.ReadBytes((int)fsObj.Length);

mcon = new MySqlConnection("server=localhost;user=root;pwd=root;database=test;");

mcon.Open();

//inserting into MySQL db

cmd = new MySqlCommand("insert into users (userid,username,userphoto) values (@userid, @username, @userphoto)", mcon);

cmd.Parameters.Add(new MySqlParameter("@userid", (object)textBox1.Text));

cmd.Parameters.Add(new MySqlParameter("@username", (object)textBox2.Text));

cmd.Parameters.Add(new MySqlParameter("@userphoto", (object)imgContent));

MessageBox.Show(cmd.ExecuteNonQuery().ToString() + " rows affected");

}

catch (MySqlException mex)

{

MessageBox.Show(mex.Message);

}

finally

{

if (binRdr != null)binRdr.Close();

binRdr = null;

if (fsObj != null)fsObj.Close();

fsObj = null;

if (cmd != null)cmd.Dispose();

cmd = null;

if (mcon != null)

{

if (mcon.State == ConnectionState.Open)

mcon.Close();

}

The above code will export the selected image into MySQL database. Please note that based on the image size we may need to define the blob datatype as "tinyblob", "blob", "mediumblob"or "longblob".

Oledb and SQL Clients

2009-11-25T18:15:00.000-08:00

While dealing with database stuff in .Net, we might worked with Oledb and SQL Clients. Here are, some of the methods which help us to get the database tables, views, primary keys...etc

OLEDB Client/ SQL Client

Namespace

System.Data.OleDb/ System.Data.SqlClient

ConnectionString

Provider=SQLOLEDB.1;Persist Security Info=False;User ID={user};Password={password};Initial Catalog={Database};Data Source={host name/IP};

Server={host name/IP}; Database={dbname}; User ID={user}; Password={sqlServerPassword};

For various connection strings, have a look at connectionstrings

Getting Table list from database

DataTable dtObj = {connection}.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new Object() {null, null, null, "Table"});

DataTable dtObj = {connection}.GetSchema("Tables");

Getting Views List

DataTable dtObj = {connection}.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new Object() {null, null, null, "View"});

DataTable dtObj = {connection}.GetSchema("Views");

Getting Stored procedures List

DataTable dtObj = {connection}.GetOleDbSchemaTable(OleDbSchemaGuid.Procedures, new Object() {null, null, null, "Views"});

DataTable dtObj = {connection}.GetSchema("Procedures");

Getting Primary keys defined in the tables

OleDbSchemaGuid.PrimaryKeys

DataTable dtObj = {connection}.GetSchema("Indexes");

Bulk insert

OledbAdapter.Update(DataTable)

SqlBulkCopy

Hence the options are vast in the Oledb and SQLClient namespaces, I have presented few things here :).

DataTable ExtendedProperties

2009-10-29T10:48:00.000-07:00

While playing in data tables in .net, it may require to have some temporary values such as records counts, primary key field name, …etc. In those situations, instead of declaring new variables in the program, it is ideal way to use “ExtendedProperties” option in datatable. The property is holding the collection (hashtable) values.

Here is the syntax;

DataTable.ExtendedProperties.Add (object key, object value);

Examples;
DataTable dtObj = new DataTable("employees");
dtObj.ExtendedProperties.Add("totalCount", 500);
dtObj.ExtendedProperties.Add("primaryKey", "employee_id");
dtObj.ExtendedProperties.Add("createdDate", DateTime.Now);

For retrieving assigned properties,
int iCount = Convert.ToInt32(dtObj.ExtendedProperties["totalCount"].ToString());

So simple and effective property.

SQL Server Editions

2009-10-26T10:04:00.000-07:00

Recently I have read an article about Microsoft SQL Server editions. It made surprise for me that Microsoft has been released 10 different versions of SQL Server. Here I am giving some of the key points on the editions.

SQL Server Compact Edition (SQL CE)

The compact edition is an embedded database engine. It is limited to 4GB maximum database size and cannot be run as a Windows service, Compact Edition must be hosted by the application using it.

SQL Server Developer Edition

SQL Server Developer Edition includes the same features as SQL Server Enterprise Edition, but is limited by the license to be only used as a development and test system, and not as production server.

SQL Server 2005 Embedded Edition (SSEE)

SQL Server 2005 Embedded Edition is a specially configured named instance of the SQL Server Express database engine which can be accessed only by certain Windows Services.

SQL Server Enterprise Edition

SQL Server Enterprise Edition is the full-featured edition of SQL Server, including both the core database engine and add-on services, while including a range of tools for creating and managing a SQL Server cluster.

SQL Server Evaluation Edition

SQL Server Evaluation Edition, also known as the Trial Edition, has all the features of the Enterprise Edition, but is limited to 180 days, after which the tools will continue to run, but the server services will be stopped.

SQL Server Express Edition

SQL Server Express Edition is a scaled down, free edition of SQL Server, which includes the core database engine. While there are no limitations on the number of databases or users supported, it is limited to using one processor, 1 GB memory and 4 GB database files. The entire database is stored in a single .mdf file.

SQL Server Fast Track

SQL Server Fast Track is specifically for enterprise-scale data warehousing storage and business intelligence processing, and runs on reference-architecture hardware that is optimized for Fast Track.

SQL Server Standard Edition

SQL Server Standard edition includes the core database engine, along with the stand-alone services. It differs from Enterprise edition in that it supports fewer active instances (number of nodes in a cluster) and does not include some high-availability functions such as hot-add memory (allowing memory to be added while the server is still running), and parallel indexes.

SQL Server Web Edition

SQL Server Web Edition is a low-TCO option for Web hosting.

SQL Server Workgroup Edition

SQL Server Workgroup Edition includes the core database functionality but does not include the additional services.

For detailed history of SQL Server, please have a look at

http://en.wikipedia.org/wiki/Microsoft_SQL_Server