A mobile database is a database than can be connected to by a mobile computing device over a mobile network. The client and server have wireless connections. A cache is maintained to hold frequent data and transactions so that they are not lost due to connection failure. A database is a structured way to organize information. This could be a list of contacts, price information or distance travelled.

The use of laptops, mobiles and PDAs is increasing and likely to increase in the future[citation needed] with more and more applications residing in the mobile systems. While those same analysts can’t tell us exactly which applications will be the most popular, it is clear that a large percentage will require the use of a database of some sort. Many applications such as databases would require the ability to download information from an information repository and operate on this information even when out of range or disconnected.

An example of this is a mobile workforce. In this scenario user would require to access and update information from files in the home directories on a server or customer records from a database. This type of access and work load generated by such users is different from the traditional workloads seen in client server systems of today. With the advent of mobile databases, now users can load up their smart phones or PDAs with mobile databases to exchange mission-critical data remotely without worrying about time or distance. Mobile databases let employees enter data on the fly. Information can be synchronized with a server database at a later time.

• Mobile users must be able to work without a wireless connection due to poor or even non-existent connections.
• Applications must provide significant interactivity.
• Applications must be able to access local device/vehicle hardware, such as printers, bar code scanners, or GPS units (for mapping or Automatic Vehicle Location systems).
• Bandwidth must be conserved (a common requirement on wireless networks that charge per megabyte or data transferred).
• Users don't require access to truly live data, only recently modified data.

If your application meets any of those requirements, the chances are good that you will be required to build a mobile database application with synchronization.

Fixed hosts: Perform the transaction and data management functions with the help of database servers

Mobile units: Portable computers, move around a geographical region that is a collection of mobile cells

With regard to mobile databases Sybase Inc.’s SQL Anywhere dominates the field, with about 68 percent of the mobile database market. IBM’s DB2 Everyplace is a relational database and enterprise synchronization server that extends enterprise applications to mobile devices. Microsoft SQL Server Compact and Oracle9i Lite are similar mobile databases. Products from lesser-known vendors, such as SQLBase from Gupta Technologies LLC of Redwood Shores, Calif., HanDBase from DDH Software Inc. of Lake Worth, Fla.and Database Viewer Plus from Cellica Corporation NY, might serve your needs equally well.

DB2e stores, retrieves, organizes and manages data on a handheld device. The data on the handheld device is synchronized to a server-based relational database management system (RDMS). DB2e is currently available for Palm OS, EPOC, Neutrino, Windows CE and embedded Linux DB2e on the handheld device includes

Microsoft SQL Server Compact (SSC) is a small footprint embedded database designed for developers who target Microsoft Windows mobile-based devices or desktops. It provides synchronization with Microsoft SQL Server, programming APIs, integrated development experience through Visual Studio and a Management Studio.

SQL Anywhere offers enterprise caliber databases that scale from 64-bit servers with thousands of users down to small handheld devices. SQL Anywhere’s data exchange technologies extend information in corporate applications and enterprise systems to databases running in mission-critical frontline environments. Design and management tools within SQL Anywhere enable developers to implement and deploy frontline applications and equip administrators to easily manage and support them

SQL Anywhere Server is a high performing and embeddable relational database-management system (RDBMS) that Scales from thousands of users in server environments down to desktop and mobile applications used in widely deployed, zero-administration environments.

Ultralite UltraLite is a database-management system designed for small-footprint mobile devices such as PDAs and smart phones.

Mobilink MobiLink is a highly-scalable, session-based synchronization technology for exchanging data among relational databases and other non-relational data sources.

QAnywhere QAnywhere facilitates the development of robust and secure store-and-forward mobile messaging applications.

SQL Remote SQL Remote technology is based on a store and forward architecture that allows occasionally connected users to synchronize data between SQL Anywhere databases using a file or message transfer mechanism.

This is a complete solution for mobile or wireless applications that require the use of a relational database on the mobile client. It includes support for Win32, Windows CE, PalmOS, and EPOC database clients, integration with Oracle's Advanced Queuing (AQ) mechanism, and data and application synchronization software (to enterprise Oracle databases. The Oracle9i Lite relational database is surprisingly[citation needed] powerful. The database supports 100% Java development (through JDBC drivers and the database's native support for embedded SQLJ and Java stored procedures) as well as programming from any development tool that supports ODBC (Visual Basic, C++, Delphi, and so on).

Borland JDataStore 6 is a fast, versatile Java database for truly portable embedded, mobile, and Web server applications. Compliant with Java and SQL92 standards, the JDataStore database features a very small footprint, requires practically zero maintenance, and delivers the performance, scalability, and synchronization capabilities of a full-power database.

MobiSnap

MobiSnap, a research project that aims to support the development of SQL based applications for mobile environments, providing conquerable support for data divergence control and connectivity abstractions. MobiSnap aims at developing a middle-ware infrastructure that allows access to relational database systems from mobile computers with a clear semantics in all operational scenarios (from high to unavailable connectivity). This platform will isolate programmers from the problems related to mobility and disconnection, allowing them to easily develop new applications for mobile environments, focusing only on application specific problems. MobiSnap will be based on SQL, thereby also providing close integration to legacy information systems.

Mobile databases are highly concentrated in Retail and Logistic industry. It is increasingly[citation needed] being used in Aviation and Transportation Industry