Assembly: System.Data.OracleClient (in system.data.oracleclient.dll)
'Declaration Public NotInheritable Class OracleLob Inherits Stream Implements ICloneable, IDisposable, INullable 'Usage Dim instance As OracleLob
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();
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