Access Definition, What is Access

Microsoft Access (current full name Microsoft Office Access) is a relational database management system from Microsoft, packaged with Microsoft Office Professional which combines the relational Microsoft Jet Database Engine with a graphical user interface.

Microsoft Access can use data stored in Access/Jet, Microsoft SQL Server, Oracle, or any ODBC-compliant data container. Skilled software developers and data architects use it to develop powerful, complex application software. Relatively unskilled programmers and non-programmer "power users" can use it to build simple applications without having to deal with features they don't understand. It supports substantial object-oriented (OO) techniques but falls short of being a fully OO development tool.

Microsoft Access was also the name of a communications program from Microsoft, meant to compete with ProComm and other programs. This Microsoft Access proved a failure and was dropped. Years later Microsoft reused the name for its database software.


Microsoft Access History

Microsoft Access version 1.0 was released in November 1992.

Microsoft specified the minimum operating system for Version 1.1 as Microsoft Windows v3.0 with 4 MB of RAM. 6 MB RAM was recommended along with a minimum of 8 MB of available hard disk space (14 MB hard disk space recommended). The product was shipped on seven 1.44 MB diskettes. The manual shows a 1993 copyright date.

The software worked well with very large records sets but testing showed some circumstances caused data corruption. For example, file sizes over 700 MB were problematic. (Note that most hard disks were smaller than 700 MB at the time this was in wide use). The Getting Started manual warns about a number of circumstances where obsolete device drivers or incorrect configurations can cause data loss.

MS-Access's initial codename was Cirrus. This was developed before Visual Basic and the forms engine was called Ruby.

Bill Gates saw the protoypes and decided that the Basic language component should be co-developed as a separate expandable application. This project was called Thunder.

The two projects were developed separately as the underlying forms engines were incompatible with each other; however, these were merged together again after VBA.


Microsoft Access Usage

Access is widely used by small businesses, within departments of large corporations, and hobby programmers to create ad hoc customized systems for handling the creation and manipulation of data. Its ease of use and powerful design tools give the non-professional programmer a lot of power for little effort. However, this ease of use can be misleading. This sort of developer is often an office worker with little or no training in application or data design. Because Access makes it possible even for such developers to create usable systems, many are misled into thinking that the tool itself is limited to such applications.

Some professional application developers use Access for rapid application development, especially for the creation of prototypes and standalone applications that serve as tools for on-the-road salesmen. Access does not scale well if data access is via a network, so applications that are used by more than a handful of people tend to rely on a Client-Server based solution such as Oracle, DB2, Microsoft SQL Server, PostgreSQL, MySQL, MaxDB, or FileMaker. However, an Access "front end" (the forms, reports, queries and VB code) can be used against a host of database backends, including Access itself, Microsoft SQL Server, Oracle, and any other ODBC-compliant product. This approach allows the developer to move a matured application's data to a more powerful server without sacrificing the development already in place.

Many developers who use Microsoft Access use the Leszynski naming convention, though this is not universal; it is a programming convention, not a DBMS-enforced rule.


Microsoft Access Features

One of the benefits of Access from a programmer's perspective is its relative compatibility with SQL – queries may be viewed and edited as SQL statements, and SQL statements can be used directly in Macros and VBA Modules to manipulate Access tables. Users may mix and use both VBA and "Macros" for programming forms and logic and offers object-oriented possibilities.

The report writer in Access is capable and up to the task of sophisticated report creation. MSDE (Microsoft SQL Server Desktop Engine) 2000, a mini-version of MS SQL Server 2000, is included with the developer edition of Office XP and may be used with Access as an alternative to the Jet Database Engine.

The Access cut-and-paste functionality can make it a useful tool for connecting between other databases (for example, Oracle and Microsoft SQL Server during data or database conversions). Access comes with various import and export features that allow integration with Windows and other platform applications, several of which can be executed on demand from within applications or manually by the user. For example the very compact SNP format for sharing perfectly formatted reports with people who don't have the full Access software. It can also easily be upgraded to Microsoft SQL Server.

Unlike a complete RDBMS, the Jet Engine lacks database triggers and stored procedures. Starting in MS Access 2000 (Jet 4.0), there is a syntax that allows creating queries with parameters, in a way that looks like creating stored procedures, but these procedures are limited to one statement per procedure.[1] Microsoft Access does allow forms to contain code that is triggered as changes are made to the underlying table (as long as the modifications are done only with that form), and it is common to use pass-through queries and other techniques in Access to run stored procedures in RDBMSs that support these.

In ADP files (supported in MS Access 2000 and later), the database-related features are entirely different, because this type of file connects to a MSDE or Microsoft SQL Server, instead of using the Jet Engine. Thus, it supports the creation of nearly all objects in the underlying server (tables with constraints and triggers, views, stored procedures and UDF-s). However, only forms, reports, macros and modules are stored in the ADP file (the other objects are stored in the back-end database).


Microsoft Access Development

The programming language available in Access is, as in other products of the Microsoft Office suite, Microsoft Visual Basic for Applications. Two database access libraries of COM components are provided: the legacy Data Access Objects (DAO), only available with Access, and the new ActiveX Data Objects (ADO).

Microsoft Access is easily applied to small projects but scales poorly to large projects owing to weak security and database locking features.

All database queries, forms, and reports are stored in the database, and in keeping with the ideals of the relational model, there is no possibility of making a physically structured hierarchy with them.

One design technique is to divide an Access application between data and programs. One database should contain only tables and relationships, while another would have all programs, forms, reports and queries, and links to the first database tables. Unfortunately, Access allows no relative paths when linking, so the development environment should have the same path as the production environment (Although you can write your own "dynamic-linker" routine in VBA that can search out a certain back-end file by searching through the directory tree, if it can't find it in the current path).

This technique also allows the developer to divide the application among different files, so some structure is possible.

ACCESS Co., Ltd.

ACCESS Co., Ltd. (ACCESS Kabushiki-gaisha Akusesu) (TYO: 4813 ), founded in 1984 in Tokyo, Japan, is a company providing embedded software for connected devices, such as mobile phones, PDAs, video game consoles and set top boxes.

The company gained wide recognition for its NetFront browser product, which has been deployed in over 200 Million devices as of November 2005 (See: http://www.access-us-inc.com/news_releases/20051122a.html), and has been used as a principal element of the widely successful i-mode data service of NTT DoCoMo in Japan. It is also in use by the Sony PSP as the web browser for versions 2.0 and above.

In September 2005, ACCESS has acquired PalmSource, the owners of the Palm OS and BeOS.

ACCESS.bus

ACCESS.bus (or A.b) is a peripheral-interconnect computer bus developed by Philips in the early 1990s. It is similar in purpose to USB, in that it allows low-speed devices to be added or removed from a computer on the fly. While it was in use earlier than USB, it never became popular, largely due to considerably less corporate backing in the industry.

A.b is a physical layer definition that describes the physical cabling and connectors used in the network. The higher layers, namely the signaling and protocol issues, are already defined to be the same as Philips' I²C bus.

Compared to I²C, A.b:

adds two additional pins to provide power to the devices (+5 V and GND)
allows for only 125 devices out of I²C's 1024
supports only the 100 kbit/s "standard mode" and 10 kbit/s "low-speed mode"
The idea was to define a single standard that could be used both inside and outside a computer. A single I²C/A.b controller chip would be used inside the machine, connected on the motherboard to internal devices like the clock and battery power monitor. An A.b connector on the outside would then allow additional devices to be plugged into the bus. This way all of the low- and medium-speed devices on the machine would be driven by a single controller and protocol stack.

A.b also defined a small set of standardized device classes. These included monitors, keyboards, "locators" (pointing devices like mice and joysticks), battery monitors, and "text devices" (modems, etc.). Depending on how much intelligence the device needed, the interface in the device could leave almost all of the work to the driver. This allows A.b to scale down to price points low enough for devices like mice.

Although A.b mice and keyboards have been available (in limited fashion) for some time, the only serious attempt to use the system was by the VESA group. They needed a standardized bus for communicating device abilities between monitors and computers, and selected I²C because it required only two pins. Re-using existing "reserved" pins in the standard VGA connector allows for a complete A.b implementation (including power). A number of monitors with A.b connectors started appearing in the mid-1990s, but this was at about the same time USB was being created. So while many still use the system to communicate to the graphics card, few (if any) include the A.b connector.

Compared to USB, A.b has several advantages. One is that any device on the bus can be a master or a slave, and a protocol is defined for selecting which one a device should use under any particular circumstance. This allows devices to be plugged together with A.b without any computer. For instance, a digital camera could be plugged directly into a printer and become the master. Under USB the computer is always the master and the devices are always slaves. In order to support the same sort of device-to-device connection, USB requires additional support in the dual role OTG devices, to emulate a host and provide similar functionality (although higher data rates). Another advantage of A.b is that devices can be strung together into a single daisy-chain—A.b can support, but does not require, the use of hubs. This can reduce cable-clutter significantly.

On the downside, A.b is much slower than USB. Had IEEE 1394 (also known as FireWire) been widely available at the time, a computer with both A.b and FireWire would have been an attractive solution for all speed ranges. As it was, USB fit neatly into the niche between the two. With USB soon included in the standard motherboard control chips from Intel, A.b was pushed out onto the low-end and quickly disappeared.