是的，C# SQLHelper 可以连接多个数据库。要实现这个功能，您需要为每个数据库创建一个单独的连接字符串，并在创建 SqlHelper 实例时使用相应的连接字符串。以下是一个简单的示例：

using System;using System.Data;using System.Data.SqlClient;public class SQLHelper{private string _connectionString;public SQLHelper(string connectionString){_connectionString = connectionString;}public DataTable ExecuteQuery(string query){using (SqlConnection connection = new SqlConnection(_connectionString)){connection.Open();using (SqlCommand command = new SqlCommand(query, connection)){using (SqlDataReader reader = command.ExecuteReader()){DataTable result = new DataTable();result.Load(reader);return result;}}}}}class Program{static void Main(string[] args){string connectionString1 = "Server=Server1;Database=Database1;User Id=User1;Password=Password1;";string connectionString2 = "Server=Server2;Database=Database2;User Id=User2;Password=Password2;";SQLHelper sqlHelper1 = new SQLHelper(connectionString1);SQLHelper sqlHelper2 = new SQLHelper(connectionString2);DataTable result1 = sqlHelper1.ExecuteQuery("SELECT * FROM Table1");DataTable result2 = sqlHelper2.ExecuteQuery("SELECT * FROM Table2");Console.WriteLine("Result from Database1:");result1.Print();Console.WriteLine("\nResult from Database2:");result2.Print();}}

在这个示例中，我们创建了两个 SQLHelper 实例，分别使用不同的连接字符串连接到两个不同的数据库。然后我们分别执行查询并打印结果。