从SQL Server中读写大数据列

2009-12-25 23:16| 发布者: admin| 查看: 114| 评论: 0|原作者: 回梦游仙

/*
Author:Wu Xiuxiang;
Email:imessage@126.com
*/
public static void Main()
{
//写入大对象到SqlServer
FileStream fs = new FileStream("C:\\test.bmp",FileMode.OPen,FileAccess.Read);
BinaryReader br = new BinaryReader(fs);
SqlConnection conn = new SqlConnection("server=localhost;uid=sa;pwd=sa;database=northwind");
string cmdText = "UPDATE EMPLOYEES" +
"SET Photo=@image where EmployeeId=1";

SqlCommand cmd = new SqlCommand(cmdText,conn);
cmd.Parameters.Add("@image",SqlDbType.Image);
cmd.Parameters["@image"].Value = br.ReadBytes((int)br.BaseStream.Length);
conn.Open();
int i=cmd.ExecuteNoQuery();

//从SQL Server中读取大对象
string cmdtext = "SELECT employeeid,photo" +
" from employees where employeeid = 1";

SqlCommand cmd2 = new SqlCommand(cmdtext,conn);
FileStream rfs;
BinaryWriter rbw;
long numread;
long startIndex;
int buffSize=4096;
byte[] buff = new byte[buffSize];
conn.Open();
SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.SequentialAccess);

if(rdr.Read())
{
int empid = rdr.GetInt32(0);
fs = new FileStream("c:\\mypic.bmp",FileMode.OpenOrCreate,FileAccess.Write);
bw = new BinaryWrite(fs);

startIndex=0;
numread = rdr.GetBytes(1,startIndex,buff,0,buffSize);
while(numread==buffSize)
{
bw.Write(buff);
bw.Flush();
startIndex+=buffSize;
numread = rdr.GetBytes(1,startIndex,buff,buffSize);
}
bw.Write(buff);
bw.Flush();

bw.Close();
fs.Close();
}
rdr.Close();
conn.Close();

}

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从SQL Server中读写大数据列

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