如何从asmx Web Service管理多个ado.net数据库连接

从ASMX Web Service管理多个ADO.NET数据库连接，可以通过以下步骤实现：

创建数据库连接字符串：

在Web.config文件中，创建多个连接字符串，每个字符串对应一个数据库。例如：

  <add name="Database1" connectionString="Data Source=server1;Initial Catalog=database1;User ID=username;Password=password" providerName="System.Data.SqlClient" />
  <add name="Database2" connectionString="Data Source=server2;Initial Catalog=database2;User ID=username;Password=password" providerName="System.Data.SqlClient" />
</connectionStrings>

创建数据访问层：

为每个数据库创建一个数据访问层，每个数据访问层包含与该数据库进行交互的方法。例如：

public class Database1DataAccess
{
    public List<Customer> GetCustomers()
    {
        string connectionString = ConfigurationManager.ConnectionStrings["Database1"].ConnectionString;

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            using (SqlCommand command = new SqlCommand("SELECT * FROM Customers", connection))
            {
                using (SqlDataReader reader = command.ExecuteReader())
                {
                    List<Customer> customers = new List<Customer>();

                    while (reader.Read())
                    {
                        Customer customer = new Customer
                        {
                            ID = reader.GetInt32(0),
                            Name = reader.GetString(1)
                        };

                        customers.Add(customer);
                    }

                    return customers;
                }
            }
        }
    }
}

public class Database2DataAccess
{
    public List<Product> GetProducts()
    {
        string connectionString = ConfigurationManager.ConnectionStrings["Database2"].ConnectionString;

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            using (SqlCommand command = new SqlCommand("SELECT * FROM Products", connection))
            {
                using (SqlDataReader reader = command.ExecuteReader())
                {
                    List<Product> products = new List<Product>();

                    while (reader.Read())
                    {
                        Product product = new Product
                        {
                            ID = reader.GetInt32(0),
                            Name = reader.GetString(1),
                            Price = reader.GetDecimal(2)
                        };

                        products.Add(product);
                    }

                    return products;
                }
            }
        }
    }
}

在Web服务中使用数据访问层：

在ASMX Web服务中，使用数据访问层获取数据并返回给客户端。例如：

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.ComponentModel.ToolboxItem(false)]
public class MyWebService : System.Web.Services.WebService
{
    [WebMethod]
    public List<Customer> GetCustomers()
    {
        Database1DataAccess dataAccess = new Database1DataAccess();
        return dataAccess.GetCustomers();
    }

    [WebMethod]
    public List<Product> GetProducts()
    {
        Database2DataAccess dataAccess = new Database2DataAccess();
        return dataAccess.GetProducts();
    }
}

通过以上步骤，可以实现从ASMX Web Service管理多个ADO.NET数据库连接。