Round #738

Open a SqlConnection, run a SELECT query, and read rows.

```csharp using System; using System.Data; using System.Data.SqlClient; class Program { static void Main() { // Establish a connection to the database string connectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;"; string query = "SELECT * FROM myTable"; // Open a connection using (SqlConnection connection = new SqlConnection(connectionString)) { connection.Open(); // Create a command object using (SqlCommand command = new SqlCommand(query, connection)) { // Create a reader using (SqlDataReader reader = command.ExecuteReader()) { // Read rows while (reader.Read()) { // Print each row for (int i = 0; i < reader.FieldCount; i++) { Console.Write(reader.GetValue(i) + " "); } Console.WriteLine(); } } } } } } ```

```csharp using System; using System.Data; using System.Data.SqlClient; public class DatabaseReader { private readonly string _connectionString; public DatabaseReader(string connectionString) { _connectionString = connectionString; } public void ReadRows(string query) { try { using (var connection = new SqlConnection(_connectionString)) { connection.Open(); using (var command = new SqlCommand(query, connection)) { using (var reader = command.ExecuteReader()) { while (reader.Read()) { for (int i = 0; i < reader.FieldCount; i++) { Console.Write(reader[i] + " "); } Console.WriteLine(); } } } } } catch (SqlException ex) { Console.WriteLine("Error reading rows: " + ex.Message); } } } class Program { static void Main() { var connectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;"; var query = "SELECT * FROM myTable"; var reader = new DatabaseReader(connectionString); reader.ReadRows(query); } } ``` This C# code snippet demonstrates how to open a `SqlConnection`, execute a `SELECT` query, and read the resulting rows. Here's a step-by-step explanation: 1. **Import necessary namespaces**: The code begins by importing the necessary namespaces, including `System.Data` and `System.Data.SqlClient`, which provide classes for working with SQL Server databases. 2. **Create a `DatabaseReader` class**: The `DatabaseReader` class encapsulates the database connection and query execution logic. It takes a `connectionString` in its constructor, which is used to establish a connection to the database. 3. **Implement the `ReadRows` method**: The `ReadRows` method takes a SQL query as input, opens a connection to the database, creates a `SqlCommand` object to execute the query, and uses a `SqlDataReader` to read the resulting rows. 4. **Handle exceptions**: The code includes error handling to catch any `SqlException` that may occur during query execution. If an exception occurs, it prints an error message to the console. 5. **Create a `Main` method**: In the `Main` method, an instance of the `DatabaseReader` class is created with a sample connection string, and the `ReadRows` method is called with a sample query. Note that you should replace the placeholders in the connection string (`myServerAddress`, `myDataBase`, `myUsername`, `myPassword`, and `myTable`) with your actual database credentials and table name.