Class RDbColReadStream

class RDbColReadStream : public RReadStream;

Description

Allows any column value to be read as stream data.

Note that this is the only way to extract the contents of a Long column from a rowset.

Only one column in a rowset object can be opened for reading as a stream at a time, and while it is open no column in the same rowset object may be set using RDbColWriteStream.

Null columns result in a read stream with no data. Small numeric columns are maintained in memory as 32-bit values; hence reading a Uint8 column as a stream results in 4 bytes of stream data, not 1.

Derivation

• RReadStream - ...

• RDbColReadStream - Allows any column value to be read as stream data.

Members

Defined in RDbColReadStream:

• OpenL(const RDbRowSet &,TDbColNo)Opens the column with the specified ordinal in the specified current row in the ...
• OpenLC(const RDbRowSet &,TDbColNo)Opens the column with the specified ordinal in the specified current row in the ...

Inherited from RReadStream:

• Attach(MStreamBuf *)Sets the stream buffer source for this read stream. The existing source (if ther...
• Close()Frees resources used by the stream.
• Detach()Sets the stream buffer source for this read stream to NULL. The existing source,...
• Pop()Removes the cleanup item for this read stream object from the cleanup stack.
• PushL()Puts a cleanup item for this read stream object onto the cleanup stack. This all...
• RReadStream(MStreamBuf *)Constructs a read stream over the supplied stream buffer.
• ReadInt16L()Internalises a TInt16 value. The function reads a 16 bit value from this stre...
• ReadInt32L()Internalises a TInt32 value. The function reads a 32 bit value from this stre...
• ReadInt8L()Internalises a TInt8 value The function reads an 8 bit value from this stream...
• ReadL(RWriteStream &)Writes the content of this stream to the specified write stream.
• ReadL(RWriteStream &,TInt)Writes the content of this stream to the specified write stream.
• ReadL(TDes16 &)Reads sufficient data from this stream to fill the specified 16 bit descriptor u...
• ReadL(TDes16 &,TChar)Reads data from this stream into the 16 bit descriptor, until either the specifi...
• ReadL(TDes16 &,TInt)Reads data of specified length from this stream into the specified 16 bit descri...
• ReadL(TDes8 &)Reads sufficient data from this stream to fill the specified 8 bit descriptor up...
• ReadL(TDes8 &,TChar)Reads data from this stream into the 8 bit descriptor, until either the specifie...
• ReadL(TDes8 &,TInt)Reads data of specified length from this stream into the specified 8 bit descrip...
• ReadL(TInt)Discards data of specified length read from this stream.
• ReadL(TUint16 *,TInt)Reads data of specified length from this stream into the specified 16 bit descri...
• ReadL(TUint8 *,TInt)Reads data of specified length from this stream into the location defined by the...
• ReadReal32L()Internalises a TReal32 value. The function reads a 32 bit value from this str...
• ReadReal64L()Internalises a TReal64 value. The function reads a 64 bit value from this str...
• ReadUint16L()Internalises a TUint16 value. The function reads a 16 bit value from this str...
• ReadUint32L()Internalises a TUint32 value. The function reads a 32 bit value from this str...
• ReadUint8L()Internalises a TUint8 value. The function reads an 8 bit value from this stre...
• Release()Frees resources before abandoning the stream.
• Source()Gets the underlying stream buffer for the read stream. This provides access to t...

Capability:

Security policy note:

For a secure shared database, the caller must satisfy the read access policy for the table.

IMPORT_C void OpenL(const RDbRowSet &aView, TDbColNo aCol);

Description

Opens the column with the specified ordinal in the specified current row in the rowset. The row must have previously been read into the rowset using RDbRowSet::GetL().

Parameters

const RDbRowSet &aView The rowset which has the row and column to be read. TDbColNo aCol The column ordinal of the column to be read

Capability:

Security policy note:

For a secure shared database, the caller must satisfy the read access policy for the table.

IMPORT_C void OpenLC(const RDbRowSet &aView, TDbColNo aCol);

Description

Opens the column with the specified ordinal in the specified current row in the rowset and puts a pointer to the column on the cleanup stack.

The row must have previously been read into the rowset using RDbRowSet::GetL().

Parameters

const RDbRowSet &aView The rowset which has the row and column to be read. TDbColNo aCol The column ordinal of the column to be read.