vishual basic data base Pankaj

 OLE DB: The OLE database protocol
Allows a program to access information in any
type of data source, and it is the basis for ADO.
Data provider: databases, spreadsheets, etc.
 ADO: ActiveX Data Objects
An Interface for OLE DB.
Allow programmers to use a standard set of
objects to refer to any OLE DB data source.
 ODBC: Open Database Connectivity
A driver manager
Used for relational databases

Program
ActiveX Data Objects
OLE DB
Provider
Data Source
OLE DB
Provider
ODBC
ODBC
Data Source

 Three types of data source names
 User DSN: usable only by you and only on the
machine currently using.
 System DSN: Any one using the machine can use.
 File DSN: Can be copied and used by other
computers with the same driver installed.

 Visual Data Manager
 Data Environments
 Data Views
 Data Report Designer
 Data Projects

 Add-Ins/Visual Data Manager
 Supports: Access, dBase, FoxPro, Paradox,
ODBC, Text files.
 Creating new database
 Managing existing database
 Query Builder, Form Wizard
 DAO

 Project/More ActiveX Designer/Data
Environment
 Data Environments are designed to be the
basis of design-time and run-time data
access. They make data available to any
forms and modules in your application.

 Right Click Connection1
Click Properties to set up database connection
Click Add Command to choose record source.
 Drag and drop fields from Command1 to
form. Text box properties:
Data Source: Data Environment1
Data Member: Command1 (Note: Data
environment can support many command
objects)
Data Field

 Access command object’s Recordset
object and Recordset object’s methods.
 Recordset’s name: rs+command name.
Ex. rsCommand1
 Properties:
EOF, BOF, RecordCount
 Methods:
MoveFirst, MoveLast, MoveNext, MovePrevious

DataEnvironment1.rsCommand1.MoveNext
IF DataEnvironment1.rsCommand1.EOF THEN
DataEnvironment1.rsCommand1.MoveLast
END IF

 View/Data View Window
 An overview of the database objects you
have in a project, such as Data
Environments, connections, data links.

 Project/Add Data Report
 Features of Data Report Designer
 Drag and Drop fields from the Data Environment
to report detail section. The DataMember and
DataField properties of the text box are
automatically set.
 Drag and Drop the Command object (Must make
sure the DataSOurce and DataMember properties
of the DataReport are set properly).

‘To preview report
DataReport1.Show
‘To print
DataReport.PrintReport

 VB projects come with built-in Data
Environments and Data Report Designer.

 Three VB database objects:
 DAO, RDO, ADO
 Two ways to work with these objects:
 VB Data controls, data-bound controls
 Programming objects

 Support the Jet database
 DAO data control
 Database property
 RecordSource property: tables, queries, SQL
statement
 RecordSet Type Property: Table, Dynaset,
Snapshot
 Able to connect to data sources such as dBase,
text files, and Excel spreadsheet.

 Project/Components/Microsoft ADO 6.0
 Double Click ADO to insert ADO
 Right Click and select ADODC Properties
 General : Source of Connection
 RecordSource:
 1 – adCmdText: SQL statement
 2 – adCmdTable: Table in the database
 4 - adCmdStoredProc

 BOF Action, EOF Action
 Command TimeOut: Amount of time in
seconds the ADO control will allow for
commands to be executed on the server.
 ConnectionString
 CursorLocation: server site, client site
 CursorType
 MaxRecords: 0 means no limit.
 RecordSource

 Forward Only: Can only move forward
through the recordset (can only
MoveNext). Use the least amount of
system resources.
 Static: Can navigate in both directions.
Unable to see changes made by other
users.
 Keyset: Can see changes made by other
users (except insertions).
 Dynamic: Use most of resources, and can
see all changes made by other users.

 ReadOnly
 Optimistic: Does not lock the file until
updates are actually applied.
 BatchOptimistic: All changes be submitted
at one time.
 Pessimistic: Lock the table the entire time
that the recordset is open.

 Determines the access rights of the user.
Read
Write
ReadWrite
ShareDenyRead: Deny other from opening
connections with read permissions.
ShareDenyWrite
ShareExclusive
ShareDenyNone: Prevent others from opening
conections with any permissions.

vishual basic data base Pankaj

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