Assembly: System.Data.OracleClient (in system.data.oracleclient.dll)
An OracleLob differs from an OracleBFile in that the data is stored on the server instead of in a physical file in the operating system. It can also be a read-write object, unlike an OracleBFile, which is always read-only.
An OracleLob may be one of these OracleType data types:
OracleType data type
An Oracle CLOB data type that contains character data, based on the default character set on the server, with a maximum size of 4 gigabytes. This maps to String.
An Oracle NCLOB data type that contains character data, based on the national character set on the server with a maximum size of 4 gigabytes. This maps to String.
To obtain an OracleLob object, call the GetOracleLob method.
You can construct an OracleLob that is NULL using this format:
OracleLob myLob = OracleLob.Null;
This technique is used primarily to test whether a LOB returned from the server is NULL, as this example illustrates:
If(myLob == OracleLob.Null)
A NULL LOB behaves similarly to a zero-byte LOB in that Read succeeds and always returns zero bytes.
Selecting a LOB column that contains a null value returns Null.
You must begin a transaction before obtaining a temporary LOB. Otherwise, the OracleDataReader may fail to obtain data later.
You can also open a temporary LOB in Oracle by calling the DBMS_LOB.CREATETEMPORARY system stored procedure and binding a LOB output parameter. On the client side, a temporary LOB behaves like a table-based LOB. For example, to update the temporary LOB, it must be enclosed in a transaction.
The following C# example demonstrates how to open a temporary LOB.
OracleConnection connection = new OracleConnection("server=MyServer; integrated security=yes;"); connection.Open(); OracleTransaction transaction = connection.BeginTransaction(); OracleCommand command = connection.CreateCommand(); command.Transaction = transaction; command.CommandText = "declare xx blob; begin dbms_lob.createtemporary(xx, false, 0); :tempblob := xx; end;"; command.Parameters.Add(new OracleParameter("tempblob", OracleType.Blob)).Direction = ParameterDirection.Output; command.ExecuteNonQuery(); OracleLob tempLob = (OracleLob)command.Parameters.Value; byte tempbuff = new byte; tempLob.BeginBatch(OracleLobOpenMode.ReadWrite); tempLob.Write(tempbuff,0,tempbuff.Length); tempLob.EndBatch(); command.Parameters.Clear(); command.CommandText = "MyTable.MyProc"; command.CommandType = CommandType.StoredProcedure; command.Parameters.Add(new OracleParameter("ImportDoc", OracleType.Blob)).Value = tempLob; command.ExecuteNonQuery(); transaction.Commit();
Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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