Tag: c sharp

Questions Related to c sharp

Features of Read only variables
c sharp

  1. It is allocated at compile time

  2. Declaration and initialization is separated

  3. It is allocated at runtime

  4. all of these

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Correct Option: C

Int keyword targets to which .Net type?
c sharp

  1. System.Int8

  2. System.Int16

  3. System.Int32

  4. System.Int64

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Correct Option: C

Which of the following method of the command object is best suited when you have aggregate functions in a SELECT statement?

c sharp

  1. ExecuteScalar

  2. ExecuteReader

  3. ExecuteNonQuery

  4. None of the above

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Correct Option: A

AI Explanation

To answer this question, we need to understand the different methods of the command object in ADO.NET and determine which one is best suited when working with aggregate functions in a SELECT statement.

Option A) ExecuteScalar - This method is used when you want to retrieve a single value from the database, such as the result of an aggregate function. It executes the query and returns the first column of the first row in the result set. This option is correct because it allows you to retrieve the result of the aggregate function directly.

Option B) ExecuteReader - This method is used to execute a query that returns a result set, and it is typically used when you want to read multiple rows of data. While it can be used to retrieve the result of an aggregate function, it would require additional code to extract the value from the result set. Therefore, it is not the best option when you have aggregate functions in a SELECT statement.

Option C) ExecuteNonQuery - This method is used for executing SQL statements that do not return a result set, such as INSERT, UPDATE, or DELETE statements. It is not suitable for retrieving the result of an aggregate function.

Option D) None of the above - This option is incorrect because option A (ExecuteScalar) is the best method to use when you have aggregate functions in a SELECT statement.

Therefore, the correct answer is option A) ExecuteScalar. This option is correct because it is the best suited method when you have aggregate functions in a SELECT statement, as it allows you to directly retrieve the result of the aggregate function.

Which of the following is the event that is exposed by the DataTable object?

c sharp

  1. RowChanged

  2. ColumnChanged

  3. RowChanging

  4. All of above

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Correct Option: D
Explanation:

To solve this question, the user needs to have knowledge of the DataTable object and the events that it exposes.

The DataTable object is a part of the ADO.NET framework and represents a table of data in memory. It is used to store and manipulate data retrieved from a database or other data source.

Now, let's go through each option and explain why it is right or wrong:

A. RowChanged: This option is correct. The RowChanged event is exposed by the DataTable object. It is raised when a row in the DataTable has been changed.

B. ColumnChanged: This option is correct. The ColumnChanged event is exposed by the DataTable object. It is raised when a value in a column of the DataTable has been changed.

C. RowChanging: This option is correct. The RowChanging event is exposed by the DataTable object. It is raised before a row in the DataTable is about to be changed.

D. All of the above: This option is correct. All of the events mentioned in options A, B, and C are exposed by the DataTable object. These events provide different points in the data manipulation process where custom logic can be executed.

Therefore, the correct answer is:

The Answer is: D. All of the above