Embedded Visual Basic Windows Ce And Pocket Pc Mobile Applications [Electronic resources] نسخه متنی

eMbedded Visual Basic®: Windows® CE and Pocket PC Mobile Applications

By
Chris Tacke, Timothy Bassett

Table of Contentsappendix A.
Control Reference

ADOCE Control Reference

The ADOCE control is used to create and manipulate data residing in Pocket Access or SQL Server CE databases. The control is added to an eVB project via the Project/References dialog. Depending on version, it will display as "Microsoft CE ADO Control x.x", where "x.x" is the version number. The latest available version at the time of publication is 3.1. The file for the ADOCE control is adocedt30.dll or adocedt31.dll, depending on version.

Table A.17. ADOCE.Connection Properties
Property	Type	Description
Attributes	Long	Implemented only with OLEDBCE providers.
ConnectionString	String	Information on where and how the connection object should open the data source. With Pocket Access, merely provide the Pocket Access file path and name. For example, ConnectionString = "\Program Files\My Application\MyPocketAccess.cdb". Note: Make sure to localize the "Program Files" directory according to the application's needs.
Errors	Collection	Collection of all ADOCE.Errors on Connection object since Connection was opened or Connection.Errors.Clear was called. See ADOCE.Error.
Properties	Collection	Provides collection of properties about the Connection. See provider documentation as to properties available. Not implemented with Pocket Access.
Provider	String	Name of the provider for the data. Pocket Access is "CEDB".
State	ADOCE.ObjectStateEnum	Provides the open or closed state of the Connection object.
Version	String	Version number of ADOCE server DLL(s).

Table A.18. ADOCE.Connection Methods
Method	Parameters	Description
BeginTrans	None	Begins a database transaction that supports an atomic unit of work. Not implemented with Pocket Access.
Close	None	Closes the current connection.
CommitTrans	None	Commits changes to data since last BeginTrans. Not implemented with Pocket Access.
Execute	CommandText; String [RecordsAffected]; Long (ByRef) Number of records affected by data manipulation statement (Not implemented with Pocket Access) [Options]; Long Not implemented with Pocket Access.	Executes a SQL Statement statement and returns the resulting recordset.
Open	[ConnectionString]; String ConnectionString to access the data store. If left blank in ADOCE, the connection will open the Windows CE Object Store. [UserId]; String User ID for access to data store. Not implemented in Windows CE Object Store or Pocket Access. Password for user ID for [Password]; String provided access to data store. Not implemented in Windows CE Object Storeor Pocket Access.	Opens a data source for access to data.
RollbackTrans	None	Discards changes made to data since BeginTrans was invoked. Not implemented in Windows CE Object Store or Pocket Access.

Table A.19. ADOCE.Field Properties
Property	Type	Description
ActualSize	Integer	Length of the field in the data store. This can be confusing for string types, because Windows CE strings are always UNICODE; therefore, the ActualSize of the field will be twice the character length.
Attributes	Long	Bit-shifted value for information about the field. It contains information such as whether the field may be updated in its current state, whether it allows NULLs, and whether it is a primary key. Refer to ADOCE documentation for these values.
DefinedSize	Integer	Length of the field as defined when it was created. This yields the capacity of the field in length.
Name	String	Name of the field.
NumericScale (Float).	Byte	Number of digits to the left of the decimal
Precision	Integer	Number of total digits available in the field.
Type	ADOCE.DataTypeEnum	Value that relates to a member of the DataTypeEnum. The actual type of the field. For example, adDate, adInt, adVarChar.
UnderlyingValue	Variant	The value of the field before it was changed (if changed). Can be useful for auditing and dirty record detection.

Table A.20. ADOCE.Field Methods
Method	Parameters	Description
AppendChunk	Data ; Variant Information to be appended to the field.	Appends data to a binary or text field. Implemented only with an OLEDBCE provide. Version 3.1 and higher.
GetChunk	Size ; Long Number of bytes to be returned.	Returns data from a binary or text field. Implemented only with an OLEDBCE provider. Version 3.1 and higher.

Table A.21. ADOCE.Recordset Properties
Property	Type	Description
AbsolutePage	Long; Read/Write	Position of the record within the data pages.
AbsolutePosition	Long; Read/Write	The position of the current record within the recordset.
ActiveConnection	Object; ADOCE.Connection	Returns a reference to the connection used to open the recordset. If queried directly, will return the connection. ConnectionString, as ConnectionString is the default property for the ADOCE.Connection object.
BOF	Boolean; Read-only	Returns True if the AbsolutePosition is before the first record in the recordset.
Bookmark	Variant; Read/Write	If queried, returns a unique variant that if set onto the recordset will return the recordset to the same record. If set, locates the AbsolutePosition to the record where the value of Bookmark was queried from.
CursorType	Long; ADOCE. CursorTypeEnum	For Windows CE Object Store or Pocket Access, only adOpenForwardOnly and adOpenKeyset are implemented.
EditMode	Long; ADOCE. EditModeEnum Read-Only	Specifies the current state of the current record. See ADOCE.EditModeEnum.
EOF	Boolean; Read-Only	Returns True if the AbsolutePosition has been placed past the last record in the recordset.
Fields	Collection; ADOCE.Fields	Collection of all fields in the record. See ADOCE.Fields.
Filter	Variant	Returns or sets the current filtering. Only supports bookmarks and adFilterNone. Not implemented in Windows CE Object Store or Pocket Access.
Index	String\|Long	Sets or returns the currently set index of the recordset. Can only be used with base table recordset (adCmdTableDirect). Can be the name of the index or the number of the index (as created). Not implemented in Windows CE Object Store or Pocket Access.
LockType	Long;	ADOCE.LockTypeEnum
PageCount	Long; Read-Only	Number of data pages in the recordset.
PageSize	Long; Read/Write	Number of records to a page.
Properties	Collection; ADOCE.Properties	Not implemented in Windows CE Object Store or Pocket Access.
RecordCount	Long	Number of records in recordset. Can return adUnknown.
Source	String; Read-only after the recordset is opened. Write before the recordset is open	The SQL string that creates the recordset or created the recordset. Set the source before Open is called. Or, can be read after therecordset is . opened.
State	Long; ADOCE.ObjectStateEnum Read-Only	Returns the open or closed state of the recordset.

Table A.22. ADOCE.Recordset Methods
Property	Parameters	Description
AddNew	[ Fields ];Array of field to set values for. [ Values ]; Array of the values corresponding to Fields array.	Appends a new record to the recordset. Sets values of fields if arrays provided as parameters.
CancelUpdate	None	Discards any changes made to the current record.
Clone	[ LockType ]; ADOCE.LockType	Returns a copy of the recordset.
Close	None	Closes the recordset.
Delete	[ AffectRecords ]only accepts adAffectCurrent, a value of 1.	Deletes the current record.
Find	Criteria ; StringString containing the field to search upon, the comparison operator and the value. ( object. Find( "LastName = 'Smith'" [ SkipRows ]; Longoffset to start searching from current record. [ searchDirection ]; ADOCE. SearchDirectionEnum direction to search, forward, or backward. [start] ; Variant Bookmark to begin searching from.	Locates the first record matching the criteria provided.
GetRows	[Rows] ; LongNumber of rows to return. [ Start ]; Long\|VariantRecord number of Bookmark of where to start returning rows. [ Fields ]; ArrayFields to return values for.	Returns an array of the values from the recordset.
Move	NumRecords ; LongNumber of records to offset to. [Start] ; Long\|Variant Record number of Bookmark of where to start returning rows.	Move a specified offset from the current record.
MoveFirst	None	Moves to the first record of the recordset.
MoveLast	None	Moves to the last record of the recordset.
MoveNext	None	Moves to the next record of the recordset.
MovePrevious	None	Moves to the previous record of the recordset.
Open	Source ; StringTable name or SQL Statement. [ ActiveConnection ]; ADOCE. ConnectionConnection to use. [ CursorType ]; ADOCE.CursorTypeCursor type for the recordset. [ LockType ]; ADOCE.LockTypeLock type for the recordset [ Options ]; LongSee provider documentation. AdCmdTableDirect is used with SQL Server CE to provide and updateable recordset.	Opens a new recordset.
Requery	None	Refreshes the recordset.
Supports	CursorOptions ; ADOCE. CursorOptionEnum	Returns Boolean as to whether the recordset supports the requested cursor option. e.g. object. Supports (adAddNew).
Update	[ Fields ];Array of field to set values for. [ Values ]; Array of the values corresponding to Fields array.	Commits changes to record back to data store.

Table A.23. ADOCE.Error Properties
Property	Type	Description
Description	String; Read-Only	Friendly description of error that occurred.
ErrorParameters	Collection; String	Collection of errors from last execution attempt. Not implemented in Windows CE Object Store or Pocket Access.
HelpContext	Long	Not implemented in Windows CE at all.
HelpFile	String; Read-Only	File path to the help file for the error.
NativeError	Long; Read-Only	Native error returned from the data provider. Limited functionality with Windows CE Object Store or Pocket Access.
Number	Long; Read-Only	Error number as implemented in OLE.
Source	String	Name of the object that generated the error. Very limited implementation for Windows CE Object Store or Pocket Access.

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Chris Tacke; Timothy Bassett

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ADOCE Control Reference

Table A.17. ADOCE.Connection Properties

Table A.18. ADOCE.Connection Methods

Table A.19. ADOCE.Field Properties

Table A.20. ADOCE.Field Methods

Table A.21. ADOCE.Recordset Properties

Table A.22. ADOCE.Recordset Methods

Table A.23. ADOCE.Error Properties

eMbedded Visual Basic®: Windows® CE and Pocket PC Mobile Applications
By Publisher		: Sams Publishing
Pub Date	: November 07, 2001
ISBN	: 0-672-32277-3
Pages	: 416