File processing
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File Processing. Concepts Field – combination of 1 or more characters that is the smallest unit of data to be accessed Record – group of related fields File – group of related records. Databases. Data organized in a manner that allows access, retrieval and use of that data

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File Processing

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File processing

File Processing

  • Concepts

    • Field – combination of 1 or more characters that is the smallest unit of data to be accessed

    • Record – group of related fields

    • File – group of related records


Databases

Databases

  • Data organized in a manner that allows access, retrieval and use of that data

  • DBMS (data base management system)

    • Software that can create, add, delete, manipulate and retrieve data from a database.


Why dbms

Why DBMS?

  • Helps to eliminate data redundancy

    • Registrar – student files with your name address, etc.

    • Financial Aid may duplicate some of the data

    • Can be helped with centralized files and file design

  • Inconsistent data

    • Change it in 1 file was it changed in another

  • Low programmer productivity

    • DBMS can do some of the tasks that a programmer has to do with a file processing system.

      • Ex. Referential integrity rules (can’t delete a master record for a sales person until the customers assigned to that sales person have been deleted or updated)


Customer data

Customer Data


Database concepts

Database concepts

  • Columns of a table (fields or attributes)

  • Rows of table ( records)

  • Database can have multiple tables

  • Relational databases have a fields or fields in one table that relates to a primary key in another table

  • Primary key – field or fields that uniquely identify a record

  • Foreign key – field or fields in one table that relates to a primary key in another


Accessing databases in visual basic

Accessing Databases in Visual Basic

  • To access a database you use a database protocol

    • DAO – Data Access Object

    • RDO – Remote Data Object

    • ADO – ActiveX Data Object


Ways to access databases in vb

Ways to Access Databases in VB

  • Two ways to work with the protocols

    • Use built in Visual Basic Controls

      • use special controls to connect to and move through databases

      • Add the data control to a form and then set properties, methods and events

      • Simple to use but limited in what you can do.

    • Reference a library of programming objects that let you handle the protocols in code


Each data control supports sql

Each data control supports SQL

  • SQL – structured query language

    • Standard language that can add, delete, modify and retrieve data as well create a database


File processing

DAO

  • Early versions of VB did not support databases

  • By ver 4.0 Access type databases were supported – Access uses the jet database engine

  • DAO was created to support the Jet database and database programming took off with VB

  • There was also a DAO object library created


File processing

RDO

  • Originally DBMS operated on stand alone computers, but now multiple computers may share data across a network

  • Microsoft came up with a standard named ODBC (open database connectivity)

  • ODBC sets up protocols to work with non-Microsoft databases such as Oracle

  • RDO allows direct access to ODBC connections( all data does not follow ODBC specs)


Universal data access

Universal Data Access

  • Universal Data Access

    • a strategy by Microsoft to provide access to all types of data without requiring it to be stored in a standard format

      • Types of data include databases, files, Internet data

    • To implement this model an interface named COM( Component Object Modules)

      • Protocol by which different objects communicate


Ole db and ado

OLE DB and ADO

  • A standard interface for accessing information stored in many formats

  • In Visual Basic you access OLD DB through ActiveX Data Objects (ADO)

  • Controls


Intrinsic and activex controls

Intrinsic and ActiveX Controls

  • Intrinsic –

    • ex. Text box (not unique to VB but available in all windows programs through the windows API) Code to implement one is embedded in the .exe

  • ActiveX

    • code to implement it is stored in a separate file .OCX

    • File must reside on computer with your VB .exe

    • ActiveX control is independent of VB and can be used in other languages


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