用泛型創建SqlServerHelper類實現增刪改查（一）

使用泛型，可以構建對數據庫單表的基本增刪改查。

首先有一數據庫 Test_SqlServerHelper ，有2表

 

接下來創建項目，對數據庫進行增刪改查。

直接貼代碼：（SqlServerHelper.cs）

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace SqlServerHelper
{
  public static class SqlServerHelper
  {
    /// <summary>
    /// 數據庫連接字符串
    /// </summary>
    private static readonly string connString = ConfigurationManager.ConnectionStrings["Test"].ToString();  //數據庫連接字符

    /// <summary>
    /// 根據id查詢對象
    /// </summary>
    /// <typeparam name="T">對象類型</typeparam>
    /// <param name="id">對象實例的Id(泛型：類型int或string)</param>
    /// <param name="idName">條件的字段名稱（主鍵名）</param>
    /// <returns></returns>
    public static T QueryById<T, I>(I id, string idName = "Id")
    {
      Type type = typeof(T);
      string columnString = string.Join(",", type.GetProperties().Select(p => string.Format("[{0}]", p.Name)));
      string sqlString = string.Format("select {0} from [{1}] where {2}={3}", columnString, type.Name, idName, id.GetType().Name.ToString() == "String" ? ("'" + id.ToString() + "'") : id.ToString());
      var t = Activator.CreateInstance(type);
      using (SqlConnection conn = new SqlConnection(connString))
      {
        conn.Open();
        SqlCommand sqlCommand = new SqlCommand(sqlString, conn);
        SqlDataReader reader = sqlCommand.ExecuteReader();
        reader.Read();
        SetValueByProperties(type, reader, t);
      }
      return (T)t;
    }

    /// <summary>
    /// 獲取數據列表
    /// </summary>
    /// <typeparam name="T">對象類型</typeparam>
    /// <returns></returns>
    public static List<T> QueryAll<T>()
    {
      Type type = typeof(T);
      string columnString = string.Join(",", type.GetProperties().Select(p => string.Format("[{0}]", p.Name)));
      string sqlString = string.Format("select {0} from [{1}]", columnString, type.Name);
      List<T> dataList = new List<T>();
      using (SqlConnection conn=new SqlConnection(connString))
      {
        conn.Open();
        SqlCommand sqlCommand = new SqlCommand(sqlString,conn);
        SqlDataReader reader = sqlCommand.ExecuteReader();
        if (reader.HasRows)
        {
          while (reader.Read())
          {
            var t = Activator.CreateInstance(type);
            SetValueByProperties(type, reader, t);
            dataList.Add((T)t);
          }
        }
        else
        {
          return null;
        }
      }
      return dataList;
    }

    /// <summary>
    /// 插入對象
    /// </summary>
    /// <typeparam name="T">對象類型</typeparam>
    /// <param name="t">對象實例</param>
    /// <param name="idName">不插入的字段（自增鍵名）</param>
    /// <returns></returns>
    public static bool Insert<T>(T t, string idName = "Id")
    {
      Type type = typeof(T);
      string sqlString = "insert [{0}] ({1}) values ({2})";
      string columnString = string.Join(",", type.GetProperties().Where(p => p.Name != idName).Select(p => string.Format("[{0}]", p.Name)));
      string valueString = string.Join(",", type.GetProperties().Where(p => p.Name != idName).Select(p => string.Format("@{0}", p.Name)));
      sqlString = string.Format(sqlString, type.Name, columnString, valueString);
      using (SqlConnection conn = new SqlConnection(connString))
      {
        conn.Open();
        SqlCommand sqlCommand = new SqlCommand(sqlString, conn);
        SqlParameter[] sqlParameter = type.GetProperties().Where(p => p.Name != idName).Select(p=>new SqlParameter(string.Format("@{0}",p.Name),p.GetValue(t,null)??DBNull.Value)).ToArray();
        sqlCommand.Parameters.AddRange(sqlParameter);
        return sqlCommand.ExecuteNonQuery() > 0;
      }
    }

    /// <summary>
    /// 修改對象
    /// </summary>
    /// <typeparam name="T">對象類型</typeparam>
    /// <param name="t">對象實例</param>
    /// <param name="idName">自增鍵名或條件名</param>
    /// <returns></returns>
    public static bool Update<T>(T t, string idName = "Id")
    {
      Type type = typeof(T);
      string sqlString = "update [{0}] set {1} where {2}={3}";
      string setString = string.Join(",", type.GetProperties().Where(p => p.Name != idName).Select(p => string.Format("[{0}]=@{0}", p.Name)));
      sqlString = string.Format(sqlString, type.Name, setString, idName,"@"+idName);
      using (SqlConnection conn = new SqlConnection(connString))
      {
        conn.Open();
        SqlCommand sqlCommand = new SqlCommand(sqlString, conn);
        SqlParameter[] sqlParameter = type.GetProperties().Select(p => new SqlParameter(string.Format("@{0}", p.Name), p.GetValue(t, null) ?? DBNull.Value)).ToArray();
        sqlCommand.Parameters.AddRange(sqlParameter);
        return sqlCommand.ExecuteNonQuery() > 0;
      }
    }

    /// <summary>
    /// 設置值by屬性（SQLreader）
    /// </summary>
    /// <param name="type">對象類型</param>
    /// <param name="reader">sqlreader</param>
    /// <param name="t">對象</param>
    private static void SetValueByProperties(Type type, SqlDataReader reader, object t)
    {
      foreach (var item in type.GetProperties())
      {
        if (reader[item.Name] is DBNull) //判空
        {
          item.SetValue(t, null);
        }
        else
        {
          item.SetValue(t, reader[item.Name]);
        }
      }
    }
  }
}

 

這里使用二個數據庫表類實體：（我是通過工具直接在數據庫上導出來的）

Dt_Fruits.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace SqlServerHelper
{
    public class Dt_Fruits
    {
        private int id;
        public int Id
        {
            get { return id; }
            set { id = value; }
        }
    
        private string name;
        public string Name
        {
            get { return name; }
            set { name = value; }
        }
    
        private int sort;
        public int Sort
        {
            get { return sort; }
            set { sort = value; }
        }
    
        private DateTime addTime;
        public DateTime AddTime
        {
            get { return addTime; }
            set { addTime = value; }
        }
    }
}

 

Dt_User.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace SqlServerHelper
{
    public class Dt_User
    {
        private int id;
        public int Id
        {
            get { return id; }
            set { id = value; }
        }
    
        private string name;
        public string Name
        {
            get { return name; }
            set { name = value; }
        }
    
        private string mob;
        public string Mob
        {
            get { return mob; }
            set { mob = value; }
        }
    
        private string sex;
        public string Sex
        {
            get { return sex; }
            set { sex = value; }
        }
    
        private DateTime birthday;
        public DateTime Birthday
        {
            get { return birthday; }
            set { birthday = value; }
        }
    
        private DateTime addTime;
        public DateTime AddTime
        {
            get { return addTime; }
            set { addTime = value; }
        }
    }
}

 

 以上都是准備工作，准備工作做好了，接下來就是，面向對象，直接操作類，快速對數據庫：增刪改查：

直接上代碼：

 //查詢所有：
      var userList = SqlServerHelper.QueryAll<Dt_User>();

      //查詢某一id:
      var oneFruits = SqlServerHelper.QueryById<Dt_Fruits,int>(1);//查到芒果的所有信息

      //修改
      oneFruits.Name = "芒果：修改";
      bool updateRes = SqlServerHelper.Update<Dt_Fruits>(oneFruits);//修改了芒果--》芒果：修改

      //添加
      var newUser = new Dt_User()
      {
        Name = "博客君",
        Sex = "男",
        Mob = "16816816888",
        Birthday = DateTime.Now,
        AddTime=DateTime.Now
      };
      bool addRes = SqlServerHelper.Insert<Dt_User>(newUser);

 

以下是增刪改查的詳細講解：

查詢整表  所有（數據量超過5000的不推薦這么查詢，一般查詢一下類型表什么的）

 //查詢所有：
      var userList = SqlServerHelper.QueryAll<Dt_User>();

 

查詢某一id  的數據

 //查詢某一id:
      var oneFruits = SqlServerHelper.QueryById<Dt_Fruits,int>(1);//查到芒果的所有信息

查詢到的數據就不截圖了

修改某一id 的數據

  //修改
      oneFruits.Name = "芒果：修改";
      bool updateRes = SqlServerHelper.Update<Dt_Fruits>(oneFruits);//修改了芒果--》芒果：修改

 

 

 添加一條數據 

 //添加
      var newUser = new Dt_User()
      {
        Name = "博客君",
        Sex = "男",
        Mob = "16816816888",
        Birthday = DateTime.Now,
        AddTime=DateTime.Now
      };
      bool addRes = SqlServerHelper.Insert<Dt_User>(newUser);

 最后數據變化：

 

 

 

是不是很棒，很輕松的對數據庫，簡單的增刪改查！

這里可能會有博友會說，哎呀，拼接SQL語句的，好像性能，或者某方面看起來不好，其實呀，ADO.net 對於數據庫訪問，底層也是對SQL語句的封裝的，好用就行了。以后如過有新表，就添加一對應新的C#模型就可以了，這種思想就衍生了現在很流行的EF框架哦。

還有！細心的朋友會發現：

我要查詢一條數據，為什么還要傳int,和1，其實是這樣的，如果數據庫主鍵名如果不是“id”，不用這樣查詢會拼接出錯誤的sql，因為id名是多變的，所以這里要傳。int,表示數據庫表的主鍵是int,對應傳就行了。假如有些數據庫表主鍵是“nvarchar，varchar 等”列如大型數據訂單id等,這時候傳string,（“10000101”）即可。

完整的寫法是這樣的：

 

 　　　　//查詢所有：
        var userList = SqlServerHelper.QueryAll<Dt_User>();

        //查詢某一id:
        var oneFruits = SqlServerHelper.QueryById<Dt_Fruits, int>(1,nameof(Dt_Fruits.Id));//查到芒果的所有信息

        //修改
        oneFruits.Name = "芒果：修改";
        bool updateRes = SqlServerHelper.Update<Dt_Fruits>(oneFruits,nameof(Dt_Fruits.Id));//修改了芒果--》芒果：修改

        //添加
        var newUser = new Dt_User()
        {
          Name = "博客君",
          Sex = "男",
          Mob = "16816816888",
          Birthday = DateTime.Now,
          AddTime = DateTime.Now
        };
        bool addRes = SqlServerHelper.Insert<Dt_User>(newUser,nameof(Dt_Fruits.Id));

 謝謝閱讀，一起學習探討！與君共勉！