Class TDbWindow

class TDbWindow;

Description

Describes the desired shape of a view's pre-evaluation window.

An instance of this class is passed to the RDbView object as part of the Prepare() function. The different constructors for TDbWindow can specify a view:

without pre-evaluation

with full pre-evaluation

with limited pre-evaluation.

Members

Defined in TDbWindow:

• ENone
• EUnlimitedNo limit on how many rows may be in the window.
• PreferredPos()constReturns the preferred position in the window of the current row marker. i.e. the...
• Size()constReturns the number of rows stored by the view.
• TDbWindow()Constructs this object with a size of ENone. This can be used to request a view ...
• TDbWindow(TInt,TInt)Constructs this object with the preferred shape. When fully evaluated, the view ...
• TDbWindow(TUnlimited)Constructs this object with a size of EUnlimited. This is used to request a comp...
• TUnlimitedDenotes a full pre-evaluation window.
• anonymous

See also:

• RDbViewGenerates rowsets from an SQL query. The query is prepared and evaluated using t...

inline TDbWindow();

Description

Constructs this object with a size of ENone. This can be used to request a view with no pre-evaluation window.

inline TDbWindow(TUnlimited);

Description

Constructs this object with a size of EUnlimited. This is used to request a completely pre-evaluated view. The constant KDbUnlimitedWindow is an instance of such a TDbWindow.

Parameters

TDbWindow::TUnlimited

IMPORT_C TDbWindow(TInt aForeSlots, TInt aRearSlots);

Description

Constructs this object with the preferred shape. When fully evaluated, the view will try to have aForeSlots rows immediately available for navigation forwards, and aRearSlots rows immediately available for navigation backwards.

Parameters

TInt aForeSlots The number of rows to evaluate ahead of the current row. TInt aRearSlots The number of rows to evaluate behind the current row.

inline TInt Size() const;

Description

Returns the number of rows stored by the view.

Return value

TInt The number of rows stored by the window. This could be one of the special values ENone or EUnlimited.

inline TInt PreferredPos() const;

Description

Returns the preferred position in the window of the current row marker. i.e. the position with the forward and backward slots as requested.

Return value

TInt The preferred position in the window. It is undefined if this is not a limited window.

TUnlimited

Description

Denotes a full pre-evaluation window.

EUnlimited No limit on how many rows may be in the window.

n/a

Description

ENone