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  • C#链接数据库增删改查的例子

    以users表为例,有三个字段,自增长的编号id,int类型;名称name,nvarchar类型,密码pwd,nvarchar类型
    首先在vs2005中引入using System.Data.SqlClient;命名空间
            /// <summary>
            /// 增加
            /// </summary>
            /// <param name="name">姓名</param>
            /// <param name="pwd">密码</param>
            /// <returns></returns>
            public int Insert(string name,string pwd)
            {
                SqlConnection conn = new SqlConnection(@"Data Source=.SQLEXPRESS;Initial Catalog=Test;Integrated Security=True");//Initial Catalog后面跟你数据库的名字,如果你的SqlServer服务器名称后面不带SQLEXPRESS,那么Data Source=.
                conn.Open();           
                string sql = "insert into users(name,pwd) values(@name,@pwd)";搜索
                SqlCommand cmd = new SqlCommand(sql,conn);
                SqlParameter parn = new SqlParameter("@name",name);
                cmd.Parameters.Add(parn);
                SqlParameter parp = new SqlParameter("@pwd", pwd);
                cmd.Parameters.Add(parn);
                int result = cmd.ExecuteNonQuery();//result接收受影响行数,也就是说result大于0的话表示添加成功
                conn.Close();
                cmd.Dispose();
                return result;
            }

            /// <summary>
            /// 删除
            /// </summary>
            /// <param name="name">姓名</param>
            /// <param name="pwd">密码</param>
            /// <returns></returns>
            public int Update(int id)
            {
                SqlConnection conn = new SqlConnection(@"Data Source=.SQLEXPRESS;Initial Catalog=Test;Integrated Security=True");//Initial Catalog后面跟你数据库的名字,如果你的SqlServer服务器名称后面不带SQLEXPRESS,那么Data Source=.
                conn.Open();
                string sql = "delete from users where id=@id";
                SqlCommand cmd = new SqlCommand(sql, conn);
                SqlParameter parn = new SqlParameter("@id", id);
                cmd.Parameters.Add(parn);       
                int result = cmd.ExecuteNonQuery();//result接收受影响行数,也就是说result大于0的话表示删除成功
                conn.Close();
                cmd.Dispose();
                return result;

            }

            /// <summary>
            /// 修改
            /// </summary>
            /// <param name="name">姓名</param>
            /// <param name="pwd">密码</param>
            /// <returns></returns>
            public int Insert(string name, string pwd,int id)
            {
                SqlConnection conn = new SqlConnection(@"Data Source=.SQLEXPRESS;Initial Catalog=Test;Integrated Security=True");//Initial Catalog后面跟你数据库的名字,如果你的SqlServer服务器名称后面不带SQLEXPRESS,那么Data Source=.
                conn.Open();           
                string sql = "update users set name=@name,pwd=@pwd where id=@id";
                SqlCommand cmd = new SqlCommand(sql, conn);
                SqlParameter parn = new SqlParameter("@name", name);
                cmd.Parameters.Add(parn);
                SqlParameter parp = new SqlParameter("@pwd", pwd);
                cmd.Parameters.Add(parn);
                SqlParameter pari = new SqlParameter("@id", id);
                cmd.Parameters.Add(pari);
                int result = cmd.ExecuteNonQuery();//result接收受影响行数,也就是说result大于0的话表示修改成功
                conn.Close();
                cmd.Dispose();
                 return result;

            }

    /// <summary>
            /// 查询
            /// </summary>
            /// <returns></returns>
            public DataTable Select()
            {
                SqlConnection conn = new SqlConnection(@"Data Source=.SQLEXPRESS;Initial Catalog=Test;Integrated Security=True");//Initial Catalog后面跟你数据库的名字,如果你的SqlServer服务器名称后面不带SQLEXPRESS,那么Data Source=.
                conn.Open();           
                string sql = "select * from users";
                SqlCommand cmd = new SqlCommand(sql, conn);
                SqlDataAdapter sda = new SqlDataAdapter(cmd);
                DataTable dt = new DataTable();
                sda.Fill(dt);          
                conn.Close();
                cmd.Dispose();
                return dt;
            }
    方法写好后,下面举一个查询的例子,在form窗体中拖一个DataGridView,然后在Load方法中
        private void Form1_Load(object sender, EventArgs e)
            {
                  dataGridView1.DataSource = Select();
            }
    这样一运行,DataGridView中就会显示数据了

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  • 原文地址:https://www.cnblogs.com/qixu/p/6140677.html
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