从一个程序出发详细研究DataReader
添加时间: 2007-4-9 2:09:25 作者: 程序员认证参考 阅读次数:41 来源: http://www.d9soft.com
using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.OleDb;
class SqlReader
{
const string connStr = "data source=bineon;user id=sa;password=87345587;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} Name:{1} PhoneNum:{2}, Address:{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} PhoneNum:{1} Address:{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();
//**************************************
//*演示带参数查询的操作,使用OleDb
//**************************************
public void hasOledbParamReader()
{
SqlCommand cmd;
cmd = conn.CreateCommand();
string sql = "select Fname,Fphone,Faddress from friend where Fid > ?";
string oledbConnStr = "Provider=sqloledb;" + connStr;
OleDbConnection oleConn = new OleDbConnection(oledbConnStr);
OleDbCommand oleCmd = new OleDbCommand(sql,oleConn);
oleCmd.Parameters.Add("nothing",15);
oleConn.Open();
OleDbDataReader oleReader = oleCmd.ExecuteReader();
while(oleReader.Read())
{
Console.WriteLine("Name:{0} PhoneNum:{1} Address:{2}",oleReader.GetString(0),oleReader.GetString(1),oleReader.GetString(2));
}
showSplit();
oleReader.Close();
oleConn.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： ");
while(reader.Read())
{
Console.WriteLine(reader[0].ToString() + " ");
}
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(" ******************************************************************** ");
}
public static void Main(string [] args)
{
SqlReader sqlreader = new SqlReader();
sqlreader.basicReader();
sqlreader.hasParamReader();
sqlreader.hasOledbParamReader();
sqlreader.outParamShow();
sqlreader.multiResult();
sqlreader.getSchema();
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