C# DataReader的详细用法

  
    

   
     1
   
     //
   
     DataReader的详细用法 
   
     

   
      
   
     2
   
      cmd.CommandText 
   
     =
   
      
   
     "
   
     GetInfo
   
     "
   
     ; 
 
   
     3
   
      cmd.CommandType 
   
     =
   
      CommandType.StoredProcedure; 
 
   
     4
   
      SqlParameter param 
   
     =
   
      cmd.Parameters.Add(
   
     "
   
     @Fid
   
     "
   
     ,
   
     16
   
     ); 
 
   
     5
   
      param 
   
     =
   
      cmd.Parameters.Add(
   
     "
   
     @Fname
   
     "
   
     ,SqlDbType.VarChar,
   
     8
   
     ); 
 
   
     6
   
      param.Direction 
   
     =
   
      ParameterDirection.Output; 
 
   
     7
   
      param 
   
     =
   
      cmd.Parameters.Add(
   
     "
   
     @Fphone
   
     "
   
     ,SqlDbType.VarChar,
   
     8
   
     ); 
 
   
     8
   
      param.Direction 
   
     =
   
      ParameterDirection.Output; 
 
   
     9
   
      conn.Open(); 
 
   
     10
   
      cmd.ExecuteNonQuery(); 
 
   
     11
   
      
   
     string
   
      Fname 
   
     =
   
      cmd.Parameters[
   
     "
   
     @Fname
   
     "
   
     ].Value.ToString(); 
 
   
     12
   
      
   
     string
   
      Fphone 
   
     =
   
      cmd.Parameters[
   
     "
   
     @Fphone
   
     "
   
     ].Value.ToString(); 
 
   
     13
   
      Console.WriteLine(Fname 
   
     +
   
      
   
     "
   
      
   
     "
   
      
   
     +
   
      Fphone); 
 
   
     14
   
      conn.Close(); 
 
   
     15
   
      showSplit(); 
 
   
     16
   
      } 
 
   
     17
   
      
 
   
     18
   
      
   
     //
   
     ************************************** 
   
     

   
      
   
     19
   
      
   
     //
   
     *演示读取多个无关记录集 
   
     

   
      
   
     20
   
      
   
     //
   
     ************************************** 
   
     

   
      
   
     21
   
      
   
     public
   
      
   
     void
   
      multiResult() 
 
   
     22
   
      { 
 
   
     23
   
      SqlCommand cmd; 
 
   
     24
   
      cmd 
   
     =
   
      conn.CreateCommand(); 
 
   
     25
   
      
   
     string
   
      sqla 
   
     =
   
      
   
     "
   
     select Fname from friend
   
     "
   
     ; 
 
   
     26
   
      
   
     string
   
      sqlb 
   
     =
   
      
   
     "
   
     select Fphone from friend
   
     "
   
     ; 
 
   
     27
   
      cmd.CommandText 
   
     =
   
      sqla 
   
     +
   
      
   
     "
   
     ;
   
     "
   
      
   
     +
   
      sqlb; 
 
   
     28
   
      conn.Open(); 
 
   
     29
   
      SqlDataReader reader
   
     =
   
      cmd.ExecuteReader(); 
 
   
     30
   
      
   
     int
   
      i 
   
     =
   
      
   
     1
   
     ; 
 
   
     31
   
      
   
     do
   
      
 
   
     32
   
      { 
 
   
     33
   
      Console.WriteLine(
   
     "
   
     第
   
     "
   
      
   
     +
   
      i.ToString() 
   
     +
   
      
   
     "
   
     个记录集内容如下：\n
   
     "
   
     ); 
 
   
     34
   
      
   
     while
   
     (reader.Read()) 
 
   
     35
   
      { 
 
   
     36
   
      Console.WriteLine(reader[
   
     0
   
     ].ToString() 
   
     +
   
      
   
     "
   
     \t
   
     "
   
     ); 
 
   
     37
   
      } 
 
   
     38
   
      i
   
     ++
   
     ; 
 
   
     39
   
      }
   
     while
   
     (reader.NextResult()); 
   
     //
   
     NextResult()移动到下一个记录集 
   
     

   
      
   
     40
   
      reader.Close(); 
 
   
     41
   
      conn.Close(); 
 
   
     42
   
      showSplit(); 
 
   
     43
   
      } 
 
   
     44
   
      
 
   
     45
   
      
   
     //
   
     ************************************** 
   
     

   
      
   
     46
   
      
   
     //
   
     *使用DataReader获得数据库模式信息 
   
     

   
      
   
     47
   
      
   
     //
   
     ************************************** 
   
     

   
      
   
     48
   
      
   
     public
   
      
   
     void
   
      getSchema() 
 
   
     49
   
      { 
 
   
     50
   
      SqlCommand cmd; 
 
   
     51
   
      cmd 
   
     =
   
      conn.CreateCommand(); 
 
   
     52
   
      
   
     string
   
      sql 
   
     =
   
      
   
     "
   
     select Fid,Fname,Fphone from friend
   
     "
   
     ; 
 
   
     53
   
      cmd.CommandText 
   
     =
   
      sql; 
 
   
     54
   
      conn.Open(); 
 
   
     55
   
      SqlDataReader reader 
   
     =
   
      cmd.ExecuteReader(); 
 
   
     56
   
      DataTable SchemaTable 
   
     =
   
      reader.GetSchemaTable(); 
 
   
     57
   
      
 
   
     58
   
      DataRowCollection SchemaColumns 
   
     =
   
      SchemaTable.Rows; 
 
   
     59
   
      DataColumnCollection SchemaProps 
   
     =
   
      SchemaTable.Columns; 
 
   
     60
   
      
   
     foreach
   
     (DataRow SchemaColumn 
   
     in
   
      SchemaColumns) 
 
   
     61
   
      { 
 
   
     62
   
      
   
     foreach
   
     (DataColumn SchemaColumnProp 
   
     in
   
      SchemaProps) 
 
   
     63
   
      { 
 
   
     64
   
      Console.WriteLine(SchemaColumnProp.ColumnName 
   
     +
   
      
   
     "
   
     =
   
     "
   
      
   
     +
   
      SchemaColumn[SchemaColumnProp.ColumnName].ToString()); 
 
   
     65
   
      } 
 
   
     66
   
      } 
 
   
     67
   
      reader.Close(); 
 
   
     68
   
      conn.Close(); 
 
   
     69
   
      showSplit(); 
 
   
     70
   
      } 
 
   
     71
   
      
 
   
     72
   
      
   
     //
   
     ************************************** 
   
     

   
      
   
     73
   
      
   
     //
   
     *从数据库读取二进制数据的代码段 
   
     

   
      
   
     74
   
      
   
     //
   
     *该代码段只是读取二进制的片断，不是 
   
     

   
      
   
     75
   
      
   
     //
   
     *整个程序，所以不能执行，你可以把它 
   
     

   
      
   
     76
   
      
   
     //
   
     *集成到你的WinForm项目里面。 
   
     

   
      
   
     77
   
      
   
     //
   
     ************************************** 
   
     

   
      
   
     78
   
      
   
     public
   
      
   
     void
   
      getBinary() 
 
   
     79
   
      { 
 
   
     80
   
      
   
     /**//*
   
      
 81 System.IO.MemoryStream stream = new System.IO.MemoryStream(); 
 82 System.IO.BinaryWriter writer = new System.IO.BinaryWriter(stream); 
 83 int BufferSize = 1024; 
 84 byte[] Buffer = new Byte[BufferSize]; 
 85 long Offset = 0; 
 86 long BytesRead = 0; 
 87 do 
 88 { 
 89 BytesRead = reader.GetBytes(2,Offset,Buffer,0,BufferSize); 
 90 writer.Writer(Buffer,0,(int)BytesRead); 
 91 writer.Flush(); 
 92 Offset += BytesRead; 
 93 } 
 94 while(BytesRead == BufferSize); 
 95 
   
     */
   
      
 
   
     96
   
      } 
 
   
     97
   
      
 
   
     98
   
      
   
     //
   
     添加输出分隔 
   
     

   
      
   
     99
   
      
   
     private
   
      
   
     void
   
      showSplit() 

   
     100
   
      { 

   
     101
   
      Console.WriteLine(
   
     "
   
     \n********************************************************************\n
   
     "
   
     ); 

   
     102
   
      } 

   
     103
   
      

   
     104
   
      
   
     public
   
      
   
     static
   
      
   
     void
   
      Main(
   
     string
   
      [] args) 

   
     105
   
      { 

   
     106
   
      SqlReader sqlreader 
   
     =
   
      
   
     new
   
      SqlReader(); 

   
     107
   
      

   
     108
   
      sqlreader.basicReader(); 

   
     109
   
      

   
     110
   
      sqlreader.hasParamReader(); 

   
     111
   
      

   
     112
   
      sqlreader.hasOledbParamReader(); 

   
     113
   
      

   
     114
   
      sqlreader.outParamShow(); 

   
     115
   
      

   
     116
   
      sqlreader.multiResult(); 

   
     117
   
      

   
     118
   
      sqlreader.getSchema(); 

   
     119
   
      } 

   
     120
   
     }