asp.net SqlHelper数据访问层的使用

作为网站的作者，关于asp.net SqlHelper数据访问层的使用，建议按照以下步骤进行：

步骤一：安装SqlHelper NuGet包

作为Sql Server数据访问层的封装，SqlHelper NuGet包能够帮助我们在asp.net应用程序中快速构建数据访问层。所以在开始本攻略前，最好先确认你已经安装了SqlHelper NuGet包。如果没有安装，可以执行以下操作：

1. 在Visual Studio 中，右键单击你的项目，选择“管理NuGet程序包”
2. 在“NuGet程序包管理”窗口中，搜索“SqlHelper”
3. 选择“SqlHelper”并安装

示例一：如何安装SqlHelper NuGet包

1. 打开Visual Studio
2. 确认你的项目中没有安装SqlHelper，如果没有安装，则依次执行下列步骤
  1. 右键单击你的项目，选择“管理NuGet程序包”
  2. 在“NuGet程序包管理”窗口中，搜索“SqlHelper”
  3. 选择“SqlHelper”并安装
3. 安装完成后，你可以开始使用SqlHelper

步骤二：引入SqlHelper命名空间

为使用SqlHelper进行数据访问，我们需要在代码中引入SqlHelper命名空间。通常情况下，我们可以在定义数据访问类时进行引入：

using SqlHelper;

示例二：如何引入SqlHelper命名空间

// 引用SqlHelper命名空间
using SqlHelper;

public class DataAccess {
  // ...
}

步骤三：使用SqlHelper进行数据访问

完成前两个步骤后，我们已经可以使用SqlHelper进行数据访问了。下面是SqlHelper的基本使用方式：

string connectionString = "Server=(local);Database=Northwind;User ID=user_name;Password=password";

SqlHelper helper = new SqlHelper(connectionString);
DataSet ds = helper.ExecuteDataSet("SELECT * FROM Customers WHERE Country = @Country", new SqlParameter("@Country", "USA"));

上述代码中，我们首先定义数据库的连接字符串，然后创建了一个SqlHelper实例，最后调用ExecuteDataSet方法查询了数据库。其中，使用了SqlParameter进行了SQL注入攻击防护。

示例三：使用SqlHelper进行增删改查操作

using SqlHelper;
using System.Data.SqlClient;

public class DataAccess {
  private string connectionString = "Server=(local);Database=Northwind;User ID=user_name;Password=password";
  private SqlHelper helper;

  public DataAccess() {
    helper = new SqlHelper(connectionString);
  }

  // 插入一条数据
  public int InsertCustomer(Customer customer) {
    string sql = @"
      INSERT INTO Customers (CustomerID, CompanyName, ContactName, ContactTitle, Address, City, Region, PostalCode, Country, Phone, Fax) 
      VALUES (@CustomerID, @CompanyName, @ContactName, @ContactTitle, @Address, @City, @Region, @PostalCode, @Country, @Phone, @Fax);
      SELECT @@IDENTITY;";

    SqlParameter[] parameters = new SqlParameter[] {
      new SqlParameter("@CustomerID", customer.CustomerID),
      new SqlParameter("@CompanyName", customer.CompanyName),
      new SqlParameter("@ContactName", customer.ContactName),
      new SqlParameter("@ContactTitle", customer.ContactTitle),
      new SqlParameter("@Address", customer.Address),
      new SqlParameter("@City", customer.City),
      new SqlParameter("@Region", customer.Region),
      new SqlParameter("@PostalCode", customer.PostalCode),
      new SqlParameter("@Country", customer.Country),
      new SqlParameter("@Phone", customer.Phone),
      new SqlParameter("@Fax", customer.Fax)
    };

    return Convert.ToInt32(helper.ExecuteScalar(sql, parameters));
  }

  // 删除一条数据
  public void DeleteCustomer(int customerID) {
    string sql = "DELETE FROM Customers WHERE CustomerID = @CustomerID";
    SqlParameter [] parameters = new SqlParameter[] {
      new SqlParameter("@CustomerID", customerID)
    };

    helper.ExecuteNonQuery(sql, parameters);
  }

  // 更新一条数据
  public int UpdateCustomer(Customer customer) {
    string sql = @"
      UPDATE Customers 
      SET CompanyName = @CompanyName, ContactName = @ContactName, ContactTitle = @ContactTitle, Address = @Address, 
          City = @City, Region = @Region, PostalCode = @PostalCode, Country = @Country, Phone = @Phone, Fax = @Fax 
      WHERE CustomerID = @CustomerID";

    SqlParameter[] parameters = new SqlParameter[] {
      new SqlParameter("@CustomerID", customer.CustomerID),
      new SqlParameter("@CompanyName", customer.CompanyName),
      new SqlParameter("@ContactName", customer.ContactName),
      new SqlParameter("@ContactTitle", customer.ContactTitle),
      new SqlParameter("@Address", customer.Address),
      new SqlParameter("@City", customer.City),
      new SqlParameter("@Region", customer.Region),
      new SqlParameter("@PostalCode", customer.PostalCode),
      new SqlParameter("@Country", customer.Country),
      new SqlParameter("@Phone", customer.Phone),
      new SqlParameter("@Fax", customer.Fax)
    };

    return helper.ExecuteNonQuery(sql, parameters);
  }

  // 查询数据
  public List<Customer> GetCustomers(string country) {
    List<Customer> customers = new List<Customer>();

    string sql = "SELECT * FROM Customers WHERE Country = @Country";
    SqlParameter[] parameters = new SqlParameter[] {
      new SqlParameter("@Country", country)
    };

    DataSet ds = helper.ExecuteDataSet(sql, parameters);

    if (ds.Tables.Count > 0 && ds.Tables[0].Rows.Count > 0) {
      foreach (DataRow row in ds.Tables[0].Rows) {
        customers.Add(new Customer {
          CustomerID = (string)row["CustomerID"],
          CompanyName = (string)row["CompanyName"],
          ContactName = (string)row["ContactName"],
          ContactTitle = (string)row["ContactTitle"],
          Address = (string)row["Address"],
          City = (string)row["City"],
          Region = (string)row["Region"],
          PostalCode = (string)row["PostalCode"],
          Country = (string)row["Country"],
          Phone = (string)row["Phone"],
          Fax = (string)row["Fax"]
        });
      }
    }

    return customers;
  }
}

public class Customer {
  public string CustomerID { get; set; }
  public string CompanyName { get; set; }
  public string ContactName { get; set; }
  public string ContactTitle { get; set; }
  public string Address { get; set; }
  public string City { get; set; }
  public string Region { get; set; }
  public string PostalCode { get; set; }
  public string Country { get; set; }
  public string Phone { get; set; }
  public string Fax { get; set; }
}

以上就是关于使用asp.net SqlHelper数据访问层的完整攻略。希望这篇攻略对你有所帮助。