Transcript ActiveX Data Objects (ADO)

ActiveX Data Objects (ADO)
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Performs same functions as DAO with
following improvements:
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Simpler command set
Faster execution (sometimes)
Uses less memory
Consumes less disk space
Supports any database to which Access can
connect
ActiveX Data Objects (ADO)
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Connection object
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Establishes a link to a database
ADO objects should be prefixed with ADODB
Set statement is optional when assigning values
to ADO objects, if you use the New keyword
Example:
Dim cnn As New ADODB.Connection
Cnn.Open CurrentProject.Connection
OR
Set cnn = CurrentProject.Connection
ActiveX Data Objects (ADO)
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Opening a recordset
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Arguments
 Table or query
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Database connection
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SQL statements may be embedded
Usually the current one stored in the Connection
object variable
Cursor types
Lock types
ActiveX Data Objects (ADO)
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Cursor types
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adOpenForwardOnly
 Read only recordset with ability to scroll
through the records in a forward direction only
adOpenKeyset
 Requests a dynaset that can be updated
adOpenDynamic
 Updateable, but not available for Jet
databases
adOpenStatic
 Read only where updates are not visible
ActiveX Data Objects (ADO)
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Lock types
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adLockReadOnly
 No changes allowed
adLockPessimistic
 Lock the record immediately upon entering
adLockOptimistic
 Attempt to lock the record when the record is
saved
adLockBatchOptimistic
 Used for batch updating
ActiveX Data Objects (ADO)
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Update method
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Changes saved using Update, moving to another
record or closing the recordset
In DAO, only Update method saves the changes
Find method
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Replaces FindFirst, FindLast, etc. from DAO
ActiveX Data Objects (ADO)
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Edit method
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ADO automatically opens in an edit mode
DAO requires Edit method
ADO or DAO?
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ADO is a generic interface to multiple
database providers
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DAO is best performer for Jet (Access)
databases
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Useful for building client/server and web
applications
ADO has to retrieve info about the database
before it can communicate with it
ADO has security shortcomings for Jet
databases