DataReader用法

using System;

using System.Data;

using System.Data.SqlClient;

using System.Data.OleDb; 

class SqlReader

{
 const string connStr = "data source=table;user id=sa;password=dddd;initial catalog=contract";
 SqlConnection conn; 


 public SqlReader()
 {
  conn = new SqlConnection(connStr);
 }
 
 //**************************************
 //*演示DataReader的两种取值方法
 //**************************************
 public void basicReader()
 {
  string sql="select * from friend";
  SqlCommand cmd; 
  cmd = conn.CreateCommand();
  cmd.CommandText = sql;
  conn.Open();
  SqlDataReader reader = cmd.ExecuteReader();
  while(reader.Read())
  {
   Console.WriteLine("No:{0}\\tName:{1}\\tPhoneNum:{2},\\tAddress:{3}",reader.GetInt32(0).ToString(),reader.GetString(1),reader[2].ToString(),reader["Faddress"].ToString());
  }
  showSplit();
  reader.Close();
  conn.Close();
 }
 
 //**************************************
 //*演示带参数查询的操作，使用SqlCilent
 //**************************************
 public void hasParamReader()
 {
  SqlCommand cmd; 
  cmd = conn.CreateCommand();
  string sql = "select Fname,Fphone,Faddress from friend where Fid > @Fid";
  cmd.CommandText = sql;
  SqlParameter param = new SqlParameter("@Fid",SqlDbType.Int,4);
  param.Value = 15;
  cmd.Parameters.Add(param);
  conn.Open();
  //当关闭reader的时候同时关闭数据库连接
  SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
  while(reader.Read())
  {
   Console.WriteLine("Name:{0}\\tPhoneNum:{1}\\tAddress:{2}",reader.GetString(0),reader.GetString(1),reader.GetString(2));
  }
  showSplit();
  //无需关闭conn,系统会自动调用这个方法来关闭conn的。
  reader.Close(); 
 }
 
 //**************************************
 //*演示存储过程的输出参数
 //**************************************
 public void outParamShow()
 {
  SqlCommand cmd; 
  cmd = conn.CreateCommand();
  cmd.CommandText = "GetInfo";
  cmd.CommandType = CommandType.StoredProcedure;
  SqlParameter param = cmd.Parameters.Add("@Fid",16);
  param = cmd.Parameters.Add("@Fname",SqlDbType.VarChar,8);
  param.Direction = ParameterDirection.Output;
  param = cmd.Parameters.Add("@Fphone",SqlDbType.VarChar,8);
  param.Direction = ParameterDirection.Output;
  conn.Open();
  cmd.ExecuteNonQuery();
  string Fname = cmd.Parameters["@Fname"].Value.ToString();
  string Fphone = cmd.Parameters["@Fphone"].Value.ToString();
  Console.WriteLine(Fname + "  " + Fphone);
  conn.Close();
  showSplit();
 }
 
 //**************************************
 //*演示读取多个无关记录集
 //************************************** 
 public void multiResult()
 {
  SqlCommand cmd; 
  cmd = conn.CreateCommand();
  string sqla = "select Fname from friend";
  string sqlb = "select Fphone from friend";
  cmd.CommandText = sqla + ";" + sqlb;
  conn.Open();
  SqlDataReader reader= cmd.ExecuteReader();
  int i = 1;
  do
  {
   Console.WriteLine("第" + i.ToString() + "个记录集内容如下：\\n");
   while(reader.Read())
   {
    Console.WriteLine(reader[0].ToString() + "\\t");
   }
   i++;
  }while(reader.NextResult()); //NextResult()移动到下一个记录集
  reader.Close();
  conn.Close();
  showSplit();
 }
 
 //**************************************
 //*使用DataReader获得数据库模式信息
 //************************************** 
 public void getSchema()
 {
  SqlCommand cmd; 
  cmd = conn.CreateCommand();
  string sql = "select Fid,Fname,Fphone from friend";
     cmd.CommandText = sql;
     conn.Open();
     SqlDataReader reader = cmd.ExecuteReader();
     DataTable SchemaTable = reader.GetSchemaTable();
     
     DataRowCollection SchemaColumns = SchemaTable.Rows;
     DataColumnCollection SchemaProps = SchemaTable.Columns;   
     foreach(DataRow SchemaColumn in SchemaColumns)
     {
      foreach(DataColumn SchemaColumnProp in SchemaProps)
      {
       Console.WriteLine(SchemaColumnProp.ColumnName + "=" + SchemaColumn[SchemaColumnProp.ColumnName].ToString());
      }
     }
     reader.Close();
     conn.Close();
     showSplit();
 }
 
 //**************************************
 //*从数据库读取二进制数据的代码段
 //*该代码段只是读取二进制的片断，不是
 //*整个程序，所以不能执行，你可以把它
 //*集成到你的WinForm项目里面。
 //************************************** 
 public void getBinary()
 {
  /*
  System.IO.MemoryStream stream = new System.IO.MemoryStream();
  System.IO.BinaryWriter writer = new System.IO.BinaryWriter(stream);   
  int BufferSize = 1024;
  byte[] Buffer = new Byte[BufferSize];
  long Offset = 0;
  long BytesRead = 0;
  do
  {
   BytesRead = reader.GetBytes(2,Offset,Buffer,0,BufferSize);
   writer.Writer(Buffer,0,(int)BytesRead);
   writer.Flush();
   Offset += BytesRead;
  }
  while(BytesRead == BufferSize);
  */
 }
 
 //添加输出分隔
 private void showSplit()
 {
  Console.WriteLine("\\n********************************************************************\\n");
 }
 
 public static void Main(string [] args)
 {
  SqlReader sqlreader = new SqlReader();
  
  sqlreader.basicReader();
  
  sqlreader.hasParamReader();
  
  sqlreader.hasOledbParamReader();
  
  sqlreader.outParamShow();
  
  sqlreader.multiResult();
  
  sqlreader.getSchema();
 } 
}