ASP.NET(C#)连接数据库和操作数据库

首先加入命名空间using System.Data.SqlClient;
1.查询
   SqlConnection conn = new SqlConnection();
   conn = new SqlConnection();
      conn.ConnectionString = "Data Source=(local);Initial Catalog=数据库名;UserID=sa;Password=123456";
      conn.Open();
      string strsql=“select语句";
      SqlCommand cmd = new SqlCommand(strsql, conn);
      SqlDataReader sqlreader = cmd.ExecuteReader();
      while (sqlreader.Read())
      {
          txtName.Text= sqlreader["列名"].ToString();
      }
      sqlreader.Close();
      conn.Close();
2.插入、更新、删除
   SqlConnection conn = new SqlConnection();
      conn = new SqlConnection();
      conn.ConnectionString = "Data Source=(local);Initial Catalog=数据库名;UserID=sa;Password=123456";
      conn.Open();
      strsql="update语句";// strsql="插入语句";//strsql="删除语句";
      SqlCommand sqlcmd2 = new SqlCommand(strsql, conn);
      int iResult = sqlcmd2.ExecuteNonQuery();
      conn.Close();