Which namespace is commonly used for LINQ in C#?
- System.Collections
- System.Data
- System.Linq
- System.Xml
The System.Linq namespace is commonly used for LINQ in C#. It contains classes and interfaces that support LINQ query operations for various data sources such as collections, arrays, XML, and databases.
To add a new row to a DataTable, you can use the ___________ method.
- AddNewRow()
- CreateRow()
- InsertRow()
- NewRow()
The NewRow() method of the DataTable class is used to create a new DataRow with the same schema as the DataTable. This method creates a new DataRow instance but does not add it to the DataRow collection. It simply returns a reference to the new DataRow, which you can then manipulate and add to the DataTable using the Add() method.
In ADO.NET, how can you handle multiple result sets returned by a SELECT statement?
- Using the SqlCommand.ExecuteReader() method
- Using the SqlConnection.Open() method
- Using the SqlDataAdapter.Fill() method
- Using the SqlDataReader.NextResult() method
In ADO.NET, you can handle multiple result sets returned by a SELECT statement using the SqlDataReader.NextResult() method. This method advances the SqlDataReader to the next result set if available. It allows you to iterate through multiple result sets returned by the same command execution.
Scenario: You are working with an Oracle database and need to handle NULL values gracefully while reading data. Which method of the OracleDataReader would you use for this purpose?
- GetValue, to retrieve the value from the database without considering if it's NULL or not, thus potentially causing errors if not handled properly.
- HasRows, to check if the result set returned by the query contains any rows, which is unrelated to handling NULL values.
- IsDBNull, to check if the value retrieved from the database is NULL, allowing for proper handling of NULL values in the application logic.
- ReadNull, to explicitly read NULL values from the database, enabling better control over how they are handled in the application.
The IsDBNull method of OracleDataReader allows for seamless handling of NULL values by checking if a retrieved value is NULL before processing it further. This helps in avoiding runtime errors and ensures smooth execution of the application logic. Other methods like GetValue do not provide the same level of control over NULL values and may lead to unexpected behavior if not handled properly.
In ADO.NET, what does a Data Filter allow you to do with a DataView?
- Aggregate rows
- Filter rows
- Group rows
- Sort rows
A Data Filter in ADO.NET allows you to filter rows in a DataView based on specified criteria. This means you can display only the rows that meet certain conditions, such as those with specific values in certain columns or rows that satisfy a particular expression. Data Filters provide a way to customize the view of data and present only relevant information to the user.
What is data binding in the context of ADO.NET?
- Displaying data from database to user interface
- Linking database fields to controls
- Storing data in a database
- Writing SQL queries
Data binding in ADO.NET refers to the process of connecting data from a database to user interface controls, allowing for the display and manipulation of database records within the application's interface. It facilitates the seamless integration of data retrieval and presentation, enhancing the user experience and streamlining data management tasks.
When using Oracle databases, you would use the ___________ class as a command object.
- OracleCommand
- SqlCommand
- DbCommand
- OleDbCommand
The correct option is OracleCommand. When working with Oracle databases in .NET applications, the OracleCommand class is specifically designed to execute commands against an Oracle database. It provides methods and properties to facilitate database interactions, making it the appropriate choice as a command object for Oracle databases.
LINQ queries are often used for data manipulation and transformation, which contributes to ___________ code readability.
- Increased
- Decreased
- Improved
- Simplified
LINQ provides a concise and expressive syntax for querying and manipulating data, leading to improved code readability. It simplifies complex operations like filtering, sorting, and grouping, thereby making code more understandable and maintainable. Hence, the correct option is "Improved."
Which WinForms control is commonly used for displaying tabular data with data binding?
- ComboBox
- DataGridView
- ListBox
- TextBox
The DataGridView control in WinForms is commonly used for displaying tabular data with data binding. It provides a powerful and customizable way to display and edit data from various data sources such as databases or collections.
In LINQ to Entities, what is the purpose of the "Where" clause in a query?
- Filters the sequence to include only elements that satisfy a specified condition
- Groups the elements in the sequence by a specified key
- Joins two sequences based on matching keys
- Orders the sequence based on a specified key
The "Where" clause in a LINQ to Entities query is used to filter the sequence of entities to include only those elements that satisfy a specified condition. It allows you to specify conditions that must be met by the entities returned by the query, enabling precise data retrieval.