ADO.Net-
What is Microsoft ADO.NET?
Visual Studio .NET provides access to databases through the set of tools and namespaces collectively referred to as Microsoft ADO.NET
What are the 3 major types of connection objects in ADO.NET?
OleDbConnection object : Use an OleDbConnection object to connect to a Microsoft Access or third-party database, such as MySQL. OLE database connections use the OleDbDataAdapter object to perform commands and return data.
SqlConnection object : Use a SqlConnection object to connect to a Microsoft SQL Server database. SQL database connections use the SqlDataAdapter object to perform commands and return data.
OracleConnection object : Use an OracleConnection object to connect to Oracle databases. Oracle database connections use the OracleDataAdapter object to perform commands and return data. This connection object was introduced in Microsoft .NET Framework version 1.1.
List the 4 common ADO.NET Namespaces?
System.Data : Contains Classes, types, and services for creating and accessing data sets and their subordinate objects
System.Data.SqlClient : Contains Classes and types for accessing Microsoft SQL Server databases
System.Data.OracleClient : Contains Classes and types for accessing Oracle databases (Microsoft .NET Framework version 1.1 and later)
System.Data.OleDb : Contains Classes and types for accessing other databases
List all the steps in order, to access a database through ADO.NET?
1. Create a connection to the database using a connection object.
2. Invoke a command to create a DataSet object using an adapter object.
3. Use the DataSet object in code to display data or to change items in the database.
4. Invoke a command to update the database from the DataSet object using an adapter object.
5. Close the database connection if you explicitly opened it in step 2 using the Open method. Invoking commands without first invoking the Open method implicitly opens and closes the connection with each request.
Why will you usually create an ASPNET user account in the Database for an ASP.NET web application?
Web applications run using the ASPNET user account. The SQL database administrator will have to set up this account and grant it permissions before your Web application will have access to a SQL database. For file-based databases, such as Microsoft Access, you must grant permissions on the database file to the ASPNET user account using Windows file security settings.
What is the difference between DataReader and DataAdapter?
1. Data Reader is read only forward only and much faster than DataAdapter.
2. If you use DataReader you have to open and close connection explicitly where as if you use DataAdapter the connection is automatically opened and closed.
3. DataReader is connection oriented where as Data Adapter is disconnected
Can you inherit from SqlConnection Class?
No, you cannot inheirt from SqlConnection Class. SqlConnection Class is a sealed class. It is a compile time error.
Will the connection be closed, if the SqlConnection object goes out of scope?
No, If the SqlConnection goes out of scope, it won't be closed. Therefore, you must explicitly close the connection by calling Close or Dispose.
What happens if connection pooling is enabled?
If connection pooling is enabled and when you call Close or Dispose methods, then the connection is returned to the connection pool. This connection can then be resused.If connection pooling is disabled and when you call Close or Dispose methods, the underlying connection to the server is actually closed.
How do you ensure that the database connections are always closed?
To ensure that the database connections are always closed, open the connection inside of a using block, as shown in the following code fragment. Doing so ensures that the connection is automatically closed when the code exits the block.
using (SqlConnection ConnectionObject = new SqlConnection())
{
ConnectionObject.Open();
//The database connection will be closed when the control exits the using code block
}
How do you read an XML file into a DataSet?
Using the DataSet object’s ReadXML method.
When do you use ExecuteReader, ExecuteNonQuery, ExecuteScalar methods?
If the command or stored procedure that is being executed returns a set of rows, then we use ExecuteReader method.
If the command or stored procedure that is being executed returns a single value then we use ExecuteScalar method.
If the command or stored procedure performs INSERT, DELETE or UPDATE operations, then we use ExecuteNonQuery method. ExecuteNonQuery method returns an integer specifying the number of rows inserted, deleted or updated.
Can your class inherit from SqlCommand Class?
No, you cannot inheirt from SqlCommand Class. SqlCommand Class is a sealed class. It is a compile time error.
Give an example that shows how to execute a stored procedure in ADO.NET?
using (SqlConnection ConnectionObject = new SqlConnection())
{
//Specify the name of the stored procedure to execute and the Connection Object to use
SqlCommand CommandObject = new SqlCommand("StoredProcedureName", ConnectionObject);
//Specify the SQL Command type is a stored procedure
CommandObject.CommandType = CommandType.StoredProcedure;
//Open the connection
ConnectionObject.Open();
//Execute the Stored Procedure
int RecordsAffected = CommandObject.ExecuteNonQuery();
}
Can you reuse a SqlCommand object?
Yes, you can reset the CommandText property and reuse the SqlCommand object.
What are the methods that can ensure asynchronous execution of the Transact-SQL statement or stored procedure?
BeginExecuteNonQuery
BeginExecuteReader
What is SqlCommand.CommandTimeout Property used for?
CommandTimeout Property is used to Get or set the wait time before terminating the attempt to execute a command and generating an error.
//Specify the CommandTimeout property value
SqlCommand CommandObject = new SqlCommand("StoredProcedureName", ConnectionObject);
//Wait for 10 seconds to execute the Stored procedure
CommandObject.CommandTimeout = 10;
The time is in seconds. The default is 30 seconds.
How do you create an instance of SqlDataReader class?
To create an instance of SqlDataReader class, you must call the ExecuteReader method of the SqlCommand object, instead of directly using a constructor.
//Error! Cannot use SqlDataReader() constructor
//to create an instance of SqlDataReader class
SqlDataReader ReaderObject = new SqlDataReader();
//Call the ExecuteReader method of the SqlCommand object
SqlCommand CommandObject = new SqlCommand();
SqlDataReader ReaderObject = CommandObject.ExecuteReader();
Creating an instance of SqlDataReader class using SqlDataReader() constructor generates a compile time error - The type 'System.Data.SqlClient.SqlDataReader' has no constructors defined.
How do you programatically check if a specified SqlDataReader instance has been closed?
Use the IsClosed property of SqlDataReader to check if a specified SqlDataReader instance has been closed. If IsClosed property returns true, the SqlDataReader instance has been closed else not closed.
How do you get the total number of columns in the current row of a SqlDataReader instance?
FieldCount property can be used to get the total number of columns in the current row of a SqlDataReader instance.
Give an example for executing a stored procedure with parameters?
//Create the Connection Object
SqlConnection ConnectionObject = new SqlConnection(ConnectionString);
//Create the Command Object
SqlCommand CommandObject = new SqlCommand("StoredProcedureName", ConnectionObject);
//Specify to CommandObject that you intend to execute a Stored Procedure
CommandObject.CommandType = CommandType.StoredProcedure;
//Create an SQL Parameter object
SqlParameter ParameterObject = new SqlParameter();
//Specify the name of the SQL Parameter
ParameterObject.ParameterName = "Parameter1";
//Assign the Parameter value
ParameterObject.Value = "Some Value";
//Specify the Database DataType of the Parameter
ParameterObject.DbType = DbType.String;
//Specify the type of parameter - input-only, output-only, bidirectional
ParameterObject.Direction = ParameterDirection.Input;
//Associate the Parameter to the Command Object
CommandObject.Parameters.Add(ParameterObject);
//Open the connection
ConnectionObject.Open();
//Execute the command
int Records_Affected = CommandObject.ExecuteNonQuery();
//Close the Connection
ConnectionObject.Close();
What is the use of SqlParameter.Direction Property?
SqlParameter.Direction Property is used to specify the Sql Parameter type - input-only, output-only, bidirectional, or a stored procedure return value parameter. The default is Input.
How do you retrieve two tables of data at the same time by using data reader?
Include 2 select statements either in a stored procedure or in a select command and call the ExecuteReader() method on the command object. This will automatically fill the DataReader with 2 Tables of data.
The datareader will always return the data from first table only. If you want to get the second table then you need to use ReaderObject.NextResult() method. The NextResult() method will return true if there is another table. The following code shows you how do it.
//Create the SQL Query with 2 Select statements
string SQLQuery = "Select * from Customers;Select * from Employees;";
//Create the Connection Object
SqlConnection ConnectionObject = new SqlConnection(ConnectionString);
//Create the Command Object
SqlCommand CommandObject = new SqlCommand(SQLQuery, ConnectionObject);
//Open the connection
ConnectionObject.Open();
//Execute the command. Now reader object will have 2 tables of data.
SqlDataReader ReaderObject = CommandObject.ExecuteReader();
//Loop thru the tables in the DataReader object
while (ReaderObject.NextResult())
{
while (ReaderObject.Read())
{
//Do Something
}
}
//Close the Reader
ReaderObject.Close();
//Close the Connection
ConnectionObject.Close();
What are the advantages of using SQL stored procedures instead of adhoc SQL queries in an ASP.NET web application?
Better Performance : As stored procedures are precompiled objects they execute faster than SQL queries. Every time we run a SQL query, the query has to be first compiled and then executed where as a stored procedure is already compiled. Hence executing stored procedures is much faster than executing SQL queries.
Better Security : For a given stored procedure you can specify who has the rights to execute. You cannot do the same for an SQL query. Writing the SQL statements inside our code is usually not a good idea. In this way you expose your database schema (design) in the code which may be changed. Hence most of the time programmers use stored procedures instead of plain SQL statements.
Reduced Network Traffic : Stored Procedures reside on the database server. If you have to execute a Stored Procedure from your ASP.NET web application, you just specify the name of the Stored Procedure. So over the network you just send the name of the Stored Procedure. With an SQL query you have to send all the SQL statements over the network to the database server which could lead to increased network traffic.
Can you update the database using DataReader object?
No, You cannot update the database using DataReader object. DataReader is read-only, foward only. It reads one record at atime. After DataReader finishes reading the current record, it moves to the next record. There is no way you can go back to the previous record.
What is the difference between a DataReader and a DataSet?
DataReader
1. DatReader works on a Connection oriented architecture.
2. DataReader is read only, forward only. It reads one record at atime. After DataReader finishes reading the current record, it moves to the next record. There is no way you can go back to the previous record. So using a DataReader you read in forward direction only.
3. Updations are not possible with DataReader.
4. As DataReader is read only, forward only it is much faster than a DataSet.
DataSet
1. DataSet works on disconnected architecture.
2. Using a DataSet you can move in both directions. DataSet is bi directional.
3. Database can be updated from a DataSet.
4. DataSet is slower than DataReader.
Give an example scenario of using a DataSet and a DataReader?
If you want to just read and display the data(No updates, deletes, or inserts) then use a DataReader.
If you want to do a batch inserts, updates and deletes then use a DataSet.
Themes and Skins-
What is a "theme" in ASP.NET?
A "theme" is a collection of property settings that allow you to define the look of pages and controls, and then apply the look consistently across pages in a Web application, across an entire Web application, or across all Web applications on a server.
What is the extension for a skin file?
.skin
What are the 2 types of control skins in ASP.NET?
1. Default skins
2. Named skins
What is the difference between Named skins and Default skins?
A default skin automatically applies to all controls of the same type when a theme is applied to a page. A control skin is a default skin if it does not have a SkinID attribute. For example, if you create a default skin for a Calendar control, the control skin applies to all Calendar controls on pages that use the theme. (Default skins are matched exactly by control type, so that a Button control skin applies to all Button controls, but not to LinkButton controls or to controls that derive from the Button object.)
A named skin is a control skin with a SkinID property set. Named skins do not automatically apply to controls by type. Instead, you explicitly apply a named skin to a control by setting the control's SkinID property. Creating named skins allows you to set different skins for different instances of the same control in an application.
What are the 3 levels at which a theme can be applied for a web application?
1. At the page level - Use the Theme or StyleSheetTheme attribute of the @ Page directive.
2. At the application level - Can be applied to all pages in an application by setting the element in the application configuration file.
3. At the web server level - Define the element in machine.config file. This will apply the theme to all the web applications on that web server.
What is the name of the folder that contains the application themes?
App_Themes
What is a global theme?
A global theme is a theme that you can apply to all the Web sites on a server. Global themes allow you to define an overall look for your domain when you maintain multiple Web sites on the same server.
What is the difference between themes and CSS?
1. Themes can define many properties of a control or page, not just style properties. For example, using themes, you can specify the graphics for a TreeView control, the template layout of a GridView control, and so on.
2. Themes can include graphics.
3. Themes do not cascade the way style sheets do. By default, any property values defined in a theme referenced by a page's Theme property override the property values declaratively set on a control, unless you explicitly apply the theme using the StyleSheetTheme property.
4. Only one theme can be applied to each page. You cannot apply multiple themes to a page, unlike style sheets where multiple style sheets can be applied.
What are the security concerns to keep in mind when using themes?
Themes can cause security issues when they are used on your Web site. Malicious themes can be used to:
1. Alter a control's behavior so that it does not behave as expected.
2. Inject client-side script, therefore posing a cross-site scripting risk.
3. Expose sensitive information.
4. The mitigations for these common threats are:
5. Protect the global and application theme directories with proper access control settings. Only trusted users should be allowed to write files to the theme directories.
6. Do not use themes from an untrusted source. Always examine any themes from outside your organization for malicious code before using them on you Web site.
7. Do not expose the theme name in query data. Malicious users could use this information to use themes that are unknown to the developer and thereby expose sensitive information.
Arrays-
What is Microsoft ADO.NET?
Visual Studio .NET provides access to databases through the set of tools and namespaces collectively referred to as Microsoft ADO.NET
What are the 3 major types of connection objects in ADO.NET?
OleDbConnection object : Use an OleDbConnection object to connect to a Microsoft Access or third-party database, such as MySQL. OLE database connections use the OleDbDataAdapter object to perform commands and return data.
SqlConnection object : Use a SqlConnection object to connect to a Microsoft SQL Server database. SQL database connections use the SqlDataAdapter object to perform commands and return data.
OracleConnection object : Use an OracleConnection object to connect to Oracle databases. Oracle database connections use the OracleDataAdapter object to perform commands and return data. This connection object was introduced in Microsoft .NET Framework version 1.1.
List the 4 common ADO.NET Namespaces?
System.Data : Contains Classes, types, and services for creating and accessing data sets and their subordinate objects
System.Data.SqlClient : Contains Classes and types for accessing Microsoft SQL Server databases
System.Data.OracleClient : Contains Classes and types for accessing Oracle databases (Microsoft .NET Framework version 1.1 and later)
System.Data.OleDb : Contains Classes and types for accessing other databases
List all the steps in order, to access a database through ADO.NET?
1. Create a connection to the database using a connection object.
2. Invoke a command to create a DataSet object using an adapter object.
3. Use the DataSet object in code to display data or to change items in the database.
4. Invoke a command to update the database from the DataSet object using an adapter object.
5. Close the database connection if you explicitly opened it in step 2 using the Open method. Invoking commands without first invoking the Open method implicitly opens and closes the connection with each request.
Why will you usually create an ASPNET user account in the Database for an ASP.NET web application?
Web applications run using the ASPNET user account. The SQL database administrator will have to set up this account and grant it permissions before your Web application will have access to a SQL database. For file-based databases, such as Microsoft Access, you must grant permissions on the database file to the ASPNET user account using Windows file security settings.
What is the difference between DataReader and DataAdapter?
1. Data Reader is read only forward only and much faster than DataAdapter.
2. If you use DataReader you have to open and close connection explicitly where as if you use DataAdapter the connection is automatically opened and closed.
3. DataReader is connection oriented where as Data Adapter is disconnected
Can you inherit from SqlConnection Class?
No, you cannot inheirt from SqlConnection Class. SqlConnection Class is a sealed class. It is a compile time error.
Will the connection be closed, if the SqlConnection object goes out of scope?
No, If the SqlConnection goes out of scope, it won't be closed. Therefore, you must explicitly close the connection by calling Close or Dispose.
What happens if connection pooling is enabled?
If connection pooling is enabled and when you call Close or Dispose methods, then the connection is returned to the connection pool. This connection can then be resused.If connection pooling is disabled and when you call Close or Dispose methods, the underlying connection to the server is actually closed.
How do you ensure that the database connections are always closed?
To ensure that the database connections are always closed, open the connection inside of a using block, as shown in the following code fragment. Doing so ensures that the connection is automatically closed when the code exits the block.
using (SqlConnection ConnectionObject = new SqlConnection())
{
ConnectionObject.Open();
//The database connection will be closed when the control exits the using code block
}
How do you read an XML file into a DataSet?
Using the DataSet object’s ReadXML method.
When do you use ExecuteReader, ExecuteNonQuery, ExecuteScalar methods?
If the command or stored procedure that is being executed returns a set of rows, then we use ExecuteReader method.
If the command or stored procedure that is being executed returns a single value then we use ExecuteScalar method.
If the command or stored procedure performs INSERT, DELETE or UPDATE operations, then we use ExecuteNonQuery method. ExecuteNonQuery method returns an integer specifying the number of rows inserted, deleted or updated.
Can your class inherit from SqlCommand Class?
No, you cannot inheirt from SqlCommand Class. SqlCommand Class is a sealed class. It is a compile time error.
Give an example that shows how to execute a stored procedure in ADO.NET?
using (SqlConnection ConnectionObject = new SqlConnection())
{
//Specify the name of the stored procedure to execute and the Connection Object to use
SqlCommand CommandObject = new SqlCommand("StoredProcedureName", ConnectionObject);
//Specify the SQL Command type is a stored procedure
CommandObject.CommandType = CommandType.StoredProcedure;
//Open the connection
ConnectionObject.Open();
//Execute the Stored Procedure
int RecordsAffected = CommandObject.ExecuteNonQuery();
}
Can you reuse a SqlCommand object?
Yes, you can reset the CommandText property and reuse the SqlCommand object.
What are the methods that can ensure asynchronous execution of the Transact-SQL statement or stored procedure?
BeginExecuteNonQuery
BeginExecuteReader
What is SqlCommand.CommandTimeout Property used for?
CommandTimeout Property is used to Get or set the wait time before terminating the attempt to execute a command and generating an error.
//Specify the CommandTimeout property value
SqlCommand CommandObject = new SqlCommand("StoredProcedureName", ConnectionObject);
//Wait for 10 seconds to execute the Stored procedure
CommandObject.CommandTimeout = 10;
The time is in seconds. The default is 30 seconds.
How do you create an instance of SqlDataReader class?
To create an instance of SqlDataReader class, you must call the ExecuteReader method of the SqlCommand object, instead of directly using a constructor.
//Error! Cannot use SqlDataReader() constructor
//to create an instance of SqlDataReader class
SqlDataReader ReaderObject = new SqlDataReader();
//Call the ExecuteReader method of the SqlCommand object
SqlCommand CommandObject = new SqlCommand();
SqlDataReader ReaderObject = CommandObject.ExecuteReader();
Creating an instance of SqlDataReader class using SqlDataReader() constructor generates a compile time error - The type 'System.Data.SqlClient.SqlDataReader' has no constructors defined.
How do you programatically check if a specified SqlDataReader instance has been closed?
Use the IsClosed property of SqlDataReader to check if a specified SqlDataReader instance has been closed. If IsClosed property returns true, the SqlDataReader instance has been closed else not closed.
How do you get the total number of columns in the current row of a SqlDataReader instance?
FieldCount property can be used to get the total number of columns in the current row of a SqlDataReader instance.
Give an example for executing a stored procedure with parameters?
//Create the Connection Object
SqlConnection ConnectionObject = new SqlConnection(ConnectionString);
//Create the Command Object
SqlCommand CommandObject = new SqlCommand("StoredProcedureName", ConnectionObject);
//Specify to CommandObject that you intend to execute a Stored Procedure
CommandObject.CommandType = CommandType.StoredProcedure;
//Create an SQL Parameter object
SqlParameter ParameterObject = new SqlParameter();
//Specify the name of the SQL Parameter
ParameterObject.ParameterName = "Parameter1";
//Assign the Parameter value
ParameterObject.Value = "Some Value";
//Specify the Database DataType of the Parameter
ParameterObject.DbType = DbType.String;
//Specify the type of parameter - input-only, output-only, bidirectional
ParameterObject.Direction = ParameterDirection.Input;
//Associate the Parameter to the Command Object
CommandObject.Parameters.Add(ParameterObject);
//Open the connection
ConnectionObject.Open();
//Execute the command
int Records_Affected = CommandObject.ExecuteNonQuery();
//Close the Connection
ConnectionObject.Close();
What is the use of SqlParameter.Direction Property?
SqlParameter.Direction Property is used to specify the Sql Parameter type - input-only, output-only, bidirectional, or a stored procedure return value parameter. The default is Input.
How do you retrieve two tables of data at the same time by using data reader?
Include 2 select statements either in a stored procedure or in a select command and call the ExecuteReader() method on the command object. This will automatically fill the DataReader with 2 Tables of data.
The datareader will always return the data from first table only. If you want to get the second table then you need to use ReaderObject.NextResult() method. The NextResult() method will return true if there is another table. The following code shows you how do it.
//Create the SQL Query with 2 Select statements
string SQLQuery = "Select * from Customers;Select * from Employees;";
//Create the Connection Object
SqlConnection ConnectionObject = new SqlConnection(ConnectionString);
//Create the Command Object
SqlCommand CommandObject = new SqlCommand(SQLQuery, ConnectionObject);
//Open the connection
ConnectionObject.Open();
//Execute the command. Now reader object will have 2 tables of data.
SqlDataReader ReaderObject = CommandObject.ExecuteReader();
//Loop thru the tables in the DataReader object
while (ReaderObject.NextResult())
{
while (ReaderObject.Read())
{
//Do Something
}
}
//Close the Reader
ReaderObject.Close();
//Close the Connection
ConnectionObject.Close();
What are the advantages of using SQL stored procedures instead of adhoc SQL queries in an ASP.NET web application?
Better Performance : As stored procedures are precompiled objects they execute faster than SQL queries. Every time we run a SQL query, the query has to be first compiled and then executed where as a stored procedure is already compiled. Hence executing stored procedures is much faster than executing SQL queries.
Better Security : For a given stored procedure you can specify who has the rights to execute. You cannot do the same for an SQL query. Writing the SQL statements inside our code is usually not a good idea. In this way you expose your database schema (design) in the code which may be changed. Hence most of the time programmers use stored procedures instead of plain SQL statements.
Reduced Network Traffic : Stored Procedures reside on the database server. If you have to execute a Stored Procedure from your ASP.NET web application, you just specify the name of the Stored Procedure. So over the network you just send the name of the Stored Procedure. With an SQL query you have to send all the SQL statements over the network to the database server which could lead to increased network traffic.
Can you update the database using DataReader object?
No, You cannot update the database using DataReader object. DataReader is read-only, foward only. It reads one record at atime. After DataReader finishes reading the current record, it moves to the next record. There is no way you can go back to the previous record.
What is the difference between a DataReader and a DataSet?
DataReader
1. DatReader works on a Connection oriented architecture.
2. DataReader is read only, forward only. It reads one record at atime. After DataReader finishes reading the current record, it moves to the next record. There is no way you can go back to the previous record. So using a DataReader you read in forward direction only.
3. Updations are not possible with DataReader.
4. As DataReader is read only, forward only it is much faster than a DataSet.
DataSet
1. DataSet works on disconnected architecture.
2. Using a DataSet you can move in both directions. DataSet is bi directional.
3. Database can be updated from a DataSet.
4. DataSet is slower than DataReader.
Give an example scenario of using a DataSet and a DataReader?
If you want to just read and display the data(No updates, deletes, or inserts) then use a DataReader.
If you want to do a batch inserts, updates and deletes then use a DataSet.
Themes and Skins-
What is a "theme" in ASP.NET?
A "theme" is a collection of property settings that allow you to define the look of pages and controls, and then apply the look consistently across pages in a Web application, across an entire Web application, or across all Web applications on a server.
What is the extension for a skin file?
.skin
What are the 2 types of control skins in ASP.NET?
1. Default skins
2. Named skins
What is the difference between Named skins and Default skins?
A default skin automatically applies to all controls of the same type when a theme is applied to a page. A control skin is a default skin if it does not have a SkinID attribute. For example, if you create a default skin for a Calendar control, the control skin applies to all Calendar controls on pages that use the theme. (Default skins are matched exactly by control type, so that a Button control skin applies to all Button controls, but not to LinkButton controls or to controls that derive from the Button object.)
A named skin is a control skin with a SkinID property set. Named skins do not automatically apply to controls by type. Instead, you explicitly apply a named skin to a control by setting the control's SkinID property. Creating named skins allows you to set different skins for different instances of the same control in an application.
What are the 3 levels at which a theme can be applied for a web application?
1. At the page level - Use the Theme or StyleSheetTheme attribute of the @ Page directive.
2. At the application level - Can be applied to all pages in an application by setting the element in the application configuration file.
3. At the web server level - Define the element in machine.config file. This will apply the theme to all the web applications on that web server.
What is the name of the folder that contains the application themes?
App_Themes
What is a global theme?
A global theme is a theme that you can apply to all the Web sites on a server. Global themes allow you to define an overall look for your domain when you maintain multiple Web sites on the same server.
What is the difference between themes and CSS?
1. Themes can define many properties of a control or page, not just style properties. For example, using themes, you can specify the graphics for a TreeView control, the template layout of a GridView control, and so on.
2. Themes can include graphics.
3. Themes do not cascade the way style sheets do. By default, any property values defined in a theme referenced by a page's Theme property override the property values declaratively set on a control, unless you explicitly apply the theme using the StyleSheetTheme property.
4. Only one theme can be applied to each page. You cannot apply multiple themes to a page, unlike style sheets where multiple style sheets can be applied.
What are the security concerns to keep in mind when using themes?
Themes can cause security issues when they are used on your Web site. Malicious themes can be used to:
1. Alter a control's behavior so that it does not behave as expected.
2. Inject client-side script, therefore posing a cross-site scripting risk.
3. Expose sensitive information.
4. The mitigations for these common threats are:
5. Protect the global and application theme directories with proper access control settings. Only trusted users should be allowed to write files to the theme directories.
6. Do not use themes from an untrusted source. Always examine any themes from outside your organization for malicious code before using them on you Web site.
7. Do not expose the theme name in query data. Malicious users could use this information to use themes that are unknown to the developer and thereby expose sensitive information.
Arrays-
What is the difference between arrays in C# and arrays in other
programming languages?
Arrays in C# work similarly to how arrays work in most other popular languages There are, however, a few differences as listed below
1. When declaring an array in C#, the square brackets ([]) must come after the type, not the identifier. Placing the brackets after the identifier is not legal syntax in C#.
Arrays in C# work similarly to how arrays work in most other popular languages There are, however, a few differences as listed below
1. When declaring an array in C#, the square brackets ([]) must come after the type, not the identifier. Placing the brackets after the identifier is not legal syntax in C#.
int[] IntegerArray; // not int IntegerArray[];
2. Another difference is that the size of the array is not part of its type as it is in the C language. This allows you to declare an array and assign any array of int objects to it, regardless of the array's length.
int[] IntegerArray; // declare IntegerArray as an int array of any size
IntegerArray = new int[10]; // IntegerArray is a 10 element array
IntegerArray = new int[50]; // now IntegerArray is a 50 element array
What are the 3 different types of arrays that we have in C#?
1. Single Dimensional Arrays
2. Multi Dimensional Arrays also called as rectangular arrays
3. Array Of Arrays also called as jagged arrays
Are arrays in C# value types or reference types?
Reference types.
What is the base class for all arrays in C#?
System.Array
How do you sort an array in C#?
The Sort static method of the Array class can be used to sort array items.
Give an example to print the numbers in the array in descending order?
using System;
namespace ConsoleApplication
{
class Program
{
static void Main()
{
int[] Numbers = { 2, 5, 3, 1, 4 };
//Print the numbers in the array without sorting
Console.WriteLine("Printing the numbers in the array without sorting");
foreach (int i in Numbers)
{
Console.WriteLine(i);
}
//Sort and then print the numbers in the array
Console.WriteLine("Printing the numbers in the array after sorting");
Array.Sort(Numbers);
foreach (int i in Numbers)
{
Console.WriteLine(i);
}
//Print the numbers in the array in desceding order
Console.WriteLine("Printing the numbers in the array in desceding order");
Array.Reverse(Numbers);
foreach (int i in Numbers)
{
Console.WriteLine(i);
}
}
}
}
What property of an array object can be used to get the total number of elements in an array?
Length property of array object gives you the total number of elements in an array. An example is shown below.
using System;
namespace ConsoleApplication
{
class Program
{
static void Main()
{
int[] Numbers = { 2, 5, 3, 1, 4 };
Console.WriteLine("Total number of elements = " +Numbers.Length);
}
}
}
Give an example to show how to copy one array into another array?
We can use CopyTo() method to copy one array into another array. An example is shown below.
using System;
namespace ConsoleApplication
{
class Program
{
static void Main()
{
int[] Numbers = { 2, 5, 3, 1, 4 };
int[] CopyOfNumbers=new int[5];
Numbers.CopyTo(CopyOfNumbers,0);
foreach (int i in CopyOfNumbers)
{
Console.WriteLine(i);
}
}
}
}
2. Another difference is that the size of the array is not part of its type as it is in the C language. This allows you to declare an array and assign any array of int objects to it, regardless of the array's length.
int[] IntegerArray; // declare IntegerArray as an int array of any size
IntegerArray = new int[10]; // IntegerArray is a 10 element array
IntegerArray = new int[50]; // now IntegerArray is a 50 element array
What are the 3 different types of arrays that we have in C#?
1. Single Dimensional Arrays
2. Multi Dimensional Arrays also called as rectangular arrays
3. Array Of Arrays also called as jagged arrays
Are arrays in C# value types or reference types?
Reference types.
What is the base class for all arrays in C#?
System.Array
How do you sort an array in C#?
The Sort static method of the Array class can be used to sort array items.
Give an example to print the numbers in the array in descending order?
using System;
namespace ConsoleApplication
{
class Program
{
static void Main()
{
int[] Numbers = { 2, 5, 3, 1, 4 };
//Print the numbers in the array without sorting
Console.WriteLine("Printing the numbers in the array without sorting");
foreach (int i in Numbers)
{
Console.WriteLine(i);
}
//Sort and then print the numbers in the array
Console.WriteLine("Printing the numbers in the array after sorting");
Array.Sort(Numbers);
foreach (int i in Numbers)
{
Console.WriteLine(i);
}
//Print the numbers in the array in desceding order
Console.WriteLine("Printing the numbers in the array in desceding order");
Array.Reverse(Numbers);
foreach (int i in Numbers)
{
Console.WriteLine(i);
}
}
}
}
What property of an array object can be used to get the total number of elements in an array?
Length property of array object gives you the total number of elements in an array. An example is shown below.
using System;
namespace ConsoleApplication
{
class Program
{
static void Main()
{
int[] Numbers = { 2, 5, 3, 1, 4 };
Console.WriteLine("Total number of elements = " +Numbers.Length);
}
}
}
Give an example to show how to copy one array into another array?
We can use CopyTo() method to copy one array into another array. An example is shown below.
using System;
namespace ConsoleApplication
{
class Program
{
static void Main()
{
int[] Numbers = { 2, 5, 3, 1, 4 };
int[] CopyOfNumbers=new int[5];
Numbers.CopyTo(CopyOfNumbers,0);
foreach (int i in CopyOfNumbers)
{
Console.WriteLine(i);
}
}
}
}
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