public System.IO.MemoryStream BlobRead(String tableName, String columnName, String criteria)
{
System.IO.MemoryStream dataStream = new System.IO.MemoryStream();
String selectStatement = "SELECT " + columnName + " FROM " + tableName + " WHERE " + criteria;
System.Data.SqlClient.SqlCommand selectCommand = null;
System.Data.SqlClient.SqlDataReader dataReader = null;
try {
OnDemandOpen();
selectCommand = (System.Data.SqlClient.SqlCommand)CreateCommand(selectStatement);
dataReader = selectCommand.ExecuteReader(System.Data.CommandBehavior.Default);
if (dataReader.Read())
{
System.Data.SqlTypes.SqlBytes sourceBytes = dataReader.GetSqlBytes(0);
if (sourceBytes.Buffer != null)
{
dataStream = new System.IO.MemoryStream(sourceBytes.Buffer);
}
else
{
dataStream = new System.IO.MemoryStream();
}
}
}
catch (Exception sqlException) {
SetLastException(sqlException);
}
finally {
if (dataReader != null)
{
dataReader.Close();
} // end if
if (selectCommand != null)
{
selectCommand.Dispose();
} // end if
dataReader = null;
selectCommand = null;
OnDemandClose();
}
return(dataStream);
}
/// <summary>
/// 备份指定的数据表。
/// </summary>
/// <param name="Connection">已经打开的数据库连接。</param>
/// <param name="xtw">XML 书写器。</param>
/// <param name="TableName">数据表名称。</param>
private void BackupTable(System.Data.SqlClient.SqlConnection Connection, System.Xml.XmlTextWriter xtw, string TableName)
{
xtw.WriteStartElement(TableName);
System.Data.SqlClient.SqlDataReader sdr = null;
System.Data.SqlClient.SqlCommand comm = new System.Data.SqlClient.SqlCommand();
comm.Connection = Connection;
comm.CommandText = @"SELECT * FROM [" + TableName + "]";
sdr = comm.ExecuteReader();
try
{
for (int i = 0; i < sdr.FieldCount; i++)
{
xtw.WriteAttributeString(sdr.GetName(i), sdr.GetDataTypeName(i));
}
while (sdr.Read())
{
xtw.WriteStartElement("Row");
for (int i = 0; i < sdr.FieldCount; i++)
{
switch ((System.Data.SqlDbType)System.Enum.Parse(typeof(System.Data.SqlDbType), sdr.GetDataTypeName(i), true))
{
case System.Data.SqlDbType.BigInt:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.Bit:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.Date:
case System.Data.SqlDbType.DateTime:
case System.Data.SqlDbType.DateTime2:
case System.Data.SqlDbType.SmallDateTime:
case System.Data.SqlDbType.Time:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.DateTimeOffset:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.Decimal:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.Float:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.Int:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.Money:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.Char:
case System.Data.SqlDbType.Text:
case System.Data.SqlDbType.VarChar:
case System.Data.SqlDbType.NChar:
case System.Data.SqlDbType.NText:
case System.Data.SqlDbType.NVarChar:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.Real:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.SmallInt:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.SmallMoney:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.TinyInt:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.UniqueIdentifier:
xtw.WriteElementString(sdr.GetName(i), sdr[i].ToString());
break;
case System.Data.SqlDbType.Binary:
xtw.WriteElementString(sdr.GetName(i), System.Text.Encoding.UTF8.GetString(sdr.GetSqlBytes(i).Value));
break;
case System.Data.SqlDbType.VarBinary:
xtw.WriteElementString(sdr.GetName(i), System.Text.Encoding.UTF8.GetString(sdr.GetSqlBytes(i).Value));
break;
case System.Data.SqlDbType.Timestamp:
xtw.WriteElementString(sdr.GetName(i), System.Text.Encoding.UTF8.GetString(sdr.GetSqlBytes(i).Value));
break;
case System.Data.SqlDbType.Image:
xtw.WriteElementString(sdr.GetName(i), System.Text.Encoding.UTF8.GetString(sdr.GetSqlBytes(i).Value));
break;
case System.Data.SqlDbType.Structured: //此类型操作待处理
break;
case System.Data.SqlDbType.Udt: //此类型操作待处理
break;
case System.Data.SqlDbType.Variant: //此类型操作待处理
break;
case System.Data.SqlDbType.Xml: //此类型操作待处理
break;
}
}
xtw.WriteEndElement();
}
}
finally
{
sdr.Close();
}
xtw.WriteEndElement();
}
