数据库表结构：
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'Content' AND type = 'U')
DROP TABLE Content
GO
create table Content
(
--内容ID
Id bigint IDENTITY(1,1) NOT NULL,
--内容
data image default null,
CONSTRAINT PK_ContentId PRIMARY KEY CLUSTERED (Id)
)
GO
const String cnnstr = "Provider=SQLOLEDB.1;User ID=sa;Password=;Initial Catalog=MyDb;Data Source=(local)";
写入
public bool WriteContent(byte [] data)
{
OleDbConnection conn = new OleDbConnection(cnnstr);
String mySelectQuery = "insert into Content(data)values(?)";
OleDbCommand myCommand = new OleDbCommand(mySelectQuery, conn);
myCommand.CommandTimeout = 60;


OleDbParameter param = new OleDbParameter("@data", OleDbType.VarBinary, data.Length);
param.Direction = ParameterDirection.Input;
param.Value = data;

myCommand.Parameters.Add(param);

bool ret = false;
try
{
conn.Open();
myCommand.ExecuteNonQuery();
ret = true;
}
catch(Exception e)
{
String msg = e.Message;
}
finally
{
//关闭数据库连接
if((conn != null) && (conn.State != ConnectionState.Closed))
{
conn.Close();
}
}
return ret;
}
读出
private byte [] ReadContent(Int64 contentId)
{
byte [] buff = null;
OleDbConnection conn = new OleDbConnection(cnnstr );
String queryStr = String.Format("select data from Content where Id={0}", contentId);
OleDbCommand myCommand = new OleDbCommand(queryStr, conn);
myCommand.CommandTimeout = 60;
OleDbDataReader reader = null;
long dataLen = 0L;
try
{
conn.Open();
reader = myCommand.ExecuteReader();
if( reader.Read() )
{
//得到要读的数据长度，注意buff必须是空的引用
dataLen = reader.GetBytes(0, 0, buff, 0, 1);
//分配缓冲区
buff = new byte[dataLen];
//读数据
dataLen = reader.GetBytes(0, 0, buff, 0, (int)dataLen);
}
}
catch(Exception e)
{
internalError(e);
String msg = e.Message;
}
finally
{
//关闭数据集
if(reader != null && !reader.IsClosed)
reader.Close();
//关闭数据库连接
if((conn != null) && (conn.State != ConnectionState.Closed))
{
conn.Close();
}
}
return buff; }