Round #571

Find the second-highest salary in an employees table.

```csharp using System; using System.Data; using System.Linq; public class Program { public static void Main() { // Create a sample DataTable DataTable dt = new DataTable(); dt.Columns.Add("Name", typeof(string)); dt.Columns.Add("Salary", typeof(int)); dt.Rows.Add("John", 50000); dt.Rows.Add("Alice", 60000); dt.Rows.Add("Bob", 40000); dt.Rows.Add("Mary", 70000); dt.Rows.Add("Peter", 45000); // Find the second-highest salary var secondHighestSalary = dt.AsEnumerable() .OrderByDescending(r => r.Field<int>("Salary")) .Select(r => r.Field<int>("Salary")) .Distinct() .Skip(1) .FirstOrDefault(); Console.WriteLine(secondHighestSalary); } } ```

```csharp using System; using System.Data; using System.Data.SqlClient; public class EmployeeRepository { private readonly string _connectionString; public EmployeeRepository(string connectionString) { _connectionString = connectionString; } public decimal? GetSecondHighestSalary() { using (var connection = new SqlConnection(_connectionString)) { connection.Open(); var query = "SELECT DISTINCT salary FROM employees ORDER BY salary DESC OFFSET 1 ROWS FETCH NEXT 1 ROW ONLY"; using (var command = new SqlCommand(query, connection)) { try { var result = command.ExecuteScalar(); if (result == null || result == DBNull.Value) { return null; } return Convert.ToDecimal(result); } catch (SqlException ex) { Console.WriteLine($"An error occurred: {ex.Message}"); return null; } } } } } class Program { static void Main(string[] args) { var connectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;"; var repository = new EmployeeRepository(connectionString); var secondHighestSalary = repository.GetSecondHighestSalary(); if (secondHighestSalary.HasValue) { Console.WriteLine($"The second-highest salary is: {secondHighestSalary}"); } else { Console.WriteLine("No second-highest salary found."); } } } ``` This C# code retrieves the second-highest salary from an `employees` table in a database. It uses ADO.NET to connect to the database and execute a SQL query. The query selects distinct salaries, orders them in descending order, skips the first row (the highest salary), and fetches the next row (the second-highest salary). **Explanation:** 1. The `EmployeeRepository` class encapsulates the database connection and query execution. 2. The `GetSecondHighestSalary` method opens a database connection, executes the SQL query, and retrieves the result. 3. The query uses `DISTINCT` to remove duplicate salaries, `ORDER BY` to sort the salaries in descending order, `OFFSET` to skip the first row, and `FETCH NEXT` to retrieve the next row. 4. The method handles potential SQL exceptions and returns `null` if an error occurs or if no second-highest salary is found. 5. In the `Main` method, an instance of `EmployeeRepository` is created, and the `GetSecondHighestSalary` method is called to retrieve the second-highest salary. The result is then printed to the console.