ADO.NET中常用的几个对象，及访问获取数据的方法

ADO.NET 是C#语言中的核心之一。
ADO.Net的四大对象及参数的总结
1.Connection 对象

web.config配置





调用：

SqlConnection con = new SqlConnection();
con.ConnectionString = System.Web.Configuration.WebConfigurationManager.ConnectionStrings["connectionString"].ConnectionString;
con.Open();

2.Command对象

string sql = string.Format("insert into Test (username,userpwd) values('{0}','{1}')", this.txtusername.Text, this.txtpwd.Text);
SqlCommand cmd = new SqlCommand(sql, con);
cmd.CommandType = System.Data.CommandType.Text;

3.DataReader对象

示例1

SqlConnection con = new SqlConnection(System.Web.Configuration.WebConfigurationManager.ConnectionStrings["connectionString"].ConnectionString);
con.Open();
SqlCommand cmd = new SqlCommand("select * from Members", con);
try
{
SqlDataReader dr = cmd.ExecuteReader();
this.GridView1.DataSource = dr;
this.GridView1.DataBind();
}
catch (Exception ex)
{
this.lblinfo.Text = ex.Message;
}
finally
{
con.Close();
}

示例2

SqlConnection con = new SqlConnection(System.Web.Configuration.WebConfigurationManager.ConnectionStrings["connectionString"].ConnectionString);
con.Open();
SqlCommand cmd = new SqlCommand("select * from Members", con);
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
this.TextBox1.Text += dr[5].ToString() + "\t" + dr["user_account"].ToString() + "\t" + dr.GetString(6).ToString()+"\r\n";
}

4.DataAdapter对象

SqlDataAdapter da = new SqlDataAdapter("select * from Members", System.Web.Configuration.WebConfigurationManager.ConnectionStrings["connectionString"].ConnectionString);

DataSet ds = new DataSet();
da.Fill(ds, "学生信息");

this.GridView1.DataSource = ds.Tables[0];
this.GridView1.DataBind();

5.参数

//创建数据库连接
SqlConnection con = new SqlConnection();
con.ConnectionString = System.Web.Configuration.WebConfigurationManager.ConnectionStrings["connectionString"].ConnectionString;
con.Open();
//创建Command
string sql = "update test set username=@username where userpwd=@userpwd";
SqlCommand cmd = new SqlCommand(sql, con);
cmd.CommandType = System.Data.CommandType.Text;
SqlParameter spname = new SqlParameter();
spname.ParameterName = "@username";
spname.DbType = DbType.String;
spname.SqlDbType = SqlDbType.NVarChar;
spname.Size = 255;
spname.Value = this.txtusername.Text;

cmd.Parameters.Add(spname);//方式1

cmd.Parameters.Add("@userpwd", SqlDbType.NVarChar).Value = this.txtpwd.Text;//方式2

int count = cmd.ExecuteNonQuery();
con.Close();
this.lblinfo.Text = "操作成功！";