What is ActiveX Data Objects (ADO)? - Definition from ecejyredagij.ml
Cursor type adOpenKeyset is similar to adOpenDynamic, it allows all movement forward or backward through records and data changes made by other users are visible, however, any new records added or records deleted by other users are not visible. Cursor type adOpenUnspecified does not specify a cursor.
LockType mentions the type of lock to be placed when records are being edited. Optimistic locking adLockOptimistic locks records only when you are updating a record ie. Pessimistic locking adLockPessimistic locks a record as soon as you start editing, and the same record cannot be read or edited by other users until you either save or cancel changes by using the Update or CancelUpdate methods respectively.
Default type is adLockReadOnly ie. Options is a Long value used to determine how the Source argument is to be evaluated, provided it is not a Command object. Though this is an optional argument, it is used to evaluate the Source argument optimally, viz. Other values are: adCmdUnspecified - does not specify how to evaluate; adCmdText - evaluates Source as a textual definition of a command or stored procedure call; adCmdStoredProc - evaluates Source as a stored procedure name; adCmdUnknown default - type of command in the Source argument is not known; adCmdFile - evaluates Source as the file name of a persistently stored Recordset; adCmdTableDirect - evaluates Source as a table name whose columns are all returned.
You will encounter an error if there is a mis-match between the Options argument and the Source type. Create a new record using the Recordset Object's AddNew method. Create a new record in a table, using the AddNew method of the Recordset object. Syntax: RecordsetObject. AddNew FieldList, Values. Both arguments are optional. FieldList is the Field Name or ordinal position of the field, and it can be a single name or an array of names.
If FieldList is an array of names, then Values should also be an array of values for the fields, of the same number and in the same order of field names. After creating a new record using the AddNew method or after changing a field value of a record, you must use the Update method of Recordset object to save changes to the current record. After using the Update method, the current record will remain the current one. Close method. You should close a Connection, a Record or a Recordset, by using the Close method, which will free any associated system resources.
Active Recordset objects associated with the connection also get closed when you close a Connection object. Closing an object is not enough to remove it from memory, for which you need to set the object variable to Nothing, after closing the object. To close a Recordset: RecordsetObject. Close To close a Connection: ConnectionObject. Delete AffectRecords. The AffectRecords argument determines how many records will the delete method affect, with the default value being adAffectCurrent which affects the current record only.
The deleted record remains the current record even after being deleted, and you can use the Move method to move to a different record. Moving between Records in a Recordset. Move Method ADO. Move NumRecords, Start. This method moves the position of the current record as per the specified number of records NumRecords argument from a starting location Start argument value adBookmarkCurrent indicates current record, adBookmarkFirst indicates first record and adBookmarkLast indicates the last record - defalut value of this optional argument is adBookmarkCurrent.
It is necessary to specify the NumRecords argument, and if this is more than 0 the current record moves forward towards end of recordset, and if less than 0 then the current record moves backwards. Using the MoveLast method moves the current record to the last record in the set of records. MoveNext method moves the current record one position forward and MovePrevious moves the current record one position backward.
MoveFirst, RecordsetObject. MoveLast, RecordsetObject. MoveNext, RecordsetObject. Both properties return a Boolean value and are used to determine if the current record is outside the limits of the Recordset object. EOF, RecordsetObject. Count the number of Records in a Recordset. The RecordCount Property will return -1 if the number of records cannot be determined or if RecordCount is not supported by the provider or cursor type. CursorType adOpenDynamic might return -1 or return the actual count, depending on the data source.
Example of using the RecordCount property:. MsgBox RecordsetObject. Count the number of Fields.
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The Count property adoRecSet. If you have seven fields in a table, using RecordsetObject. Fields 0 will return the value of the first field. Access Fields by Item property viz. Item index.
ADO: ActiveX Data Objects by Jason T Roff
You can access fields by the Item property which refers to the field name or its position, viz. Item index , where index is the Field Name or its ordinal position. Note that the Item property is the default property of the fields collection, so omitting the Item keyword will have no effect. Fields 0. Name returns the Field name of the first field, and Recordset. The complete name of a SAS file consists of two words, separated by a period. The libref, which is the first word, indicates the library. The second word is the name of the specific SAS file.
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For example, in VLIB. OLE enables an object created by one application to be embedded in or linked to another application. OLE DB an open specification that has been developed by Microsoft for accessing both relational and nonrelational data. OLE DB interfaces can provide much of the same functionality that is provided by database management systems. Because there are different providers and each provider has multiple ways to make a connection there are many different ways to write a connection string.
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It's like the address when sending a regular mail. Depending on the origin and destination and who is going to make the transport you need to write down the address in different ways. The connection string is really just a string inside the application you pass on to the connection object. The property is passed through the Open function of the connection object. The ADO Recordset object is used to contain the set of data extracted from a database or file and is composed of records rows and fields columns.
The Recordset object is the heart of ADO. Via this object, we can select desired data. Equally important is the ability to move around inside the database. However, the functionality of the provider may impose limitations. The Open method is called on a Recordset object to open a cursor which gives you access to the records contained in the base table, the results from a query used in the examples of this tutorial , or a previously saved Recordset.
To handle events you need to create an event object and set the name of a function which then handles the event:.