Programmatic Database Access

SQL is also a database language used by programmers to write applications that access a database. The same SQL statements are used for both interactive and programmatic access, so the database access parts of a program can be tested first with interactive SQL and then embedded into the program. In contrast, traditional databases provided one set of tools for programmatic access and a separate query facility for ad hoc requests, without any synergy between the two modes of access.

Multiple Views of Data

Using SQL, the creator of a database can give different users of the database different views of its structure and contents. For example, the database can be constructed so that each user sees data only for his or her department or sales region. In addition, data from several different parts of the database can be combined and presented to the user as a simple row/column table. SQL views can thus be used to enhance the security of a database and tailor it to the particular needs of individual users.

Complete Database Language

SQL was first developed as an ad hoc query language, but its powers now go far beyond data retrieval. SQL provides a complete, consistent language for creating a database, managing its security, updating its contents, retrieving data, and sharing data among many concurrent users. SQL concepts that are learned in one part of the language can be applied to other SQL commands, making users more productive.

Dynamic Data Definition

Using SQL, the structure of a database can be changed and expanded dynamically, even while users are accessing database contents. This is a major advance over static data definition languages, which prevented access to the database while its structure was being changed. SQL thus provides maximum flexibility, allowing a database to adapt to changing requirements while online applications continue uninterrupted.

Client/Server Architecture

SQL is a natural vehicle for implementing applications using a distributed, client/ server architecture. In this role, SQL serves as the link between “front-end” computer systems optimized for user interaction and “back-end” systems specialized for database management , allowing each system to do what it does best. SQL also allows personal computers to function as front-ends to network servers or to larger minicomputer and mainframe databases, providing access to corporate data from personal computer applications. 

Enterprise Application Support

The largest enterprise applications that support the daily operation of large companies and organizations all use SQL-based databases to store and organize their data. Data about business transactions (orders, sales amounts, customers , inventory levels, payment amounts, etc.) tends to have a structured, records-and-fields format, which converts easily into the row/column format of SQL. By constructing their applications to use enterprise-class SQL databases, major application vendors eliminate the need to develop their own data management software and can benefit from existing tools and programming skills. Because every major enterprise application requires a SQL-based database for its operation, new sales of enterprise applications automatically generate “drag-along” demand for new copies of database software.

Extensibility and Object Technology

The major challenge to SQL's continued dominance as a database standard has come from the emergence of object-based programming, and the introduction of object-based databases as an extension of the broad market trend toward object-based technology.  SQL-based database vendors have responded to this challenge by slowly expanding and enhancing SQL to include object features. These “object/relational” databases, which continue to be based on SQL, have emerged as a more popular alternative to “pure object” databases and have perpetuated SQL's dominance through the last decade. The newest wave of object technology, embodied in the XML standard and web services architectures, has once again created a crop of “XML databases” and alternative query languages to challenge SQL. Previous history tends to suggest that XML-based extensions to SQL and the relational model will once again meet this challenge and insure SQL's continuing importance.

Internet Database Access

With the exploding popularity of the Internet and the World Wide Web, and their standards-based foundation, SQL found a new role in the late 1990s as an Internet data access standard. Early in the development of the Web, developers needed a way to retrieve and present database information on web pages and used SQL as a common language for database gateways. More recently, the emergence of three-tiered Internet architectures with distinct thin client, application server and database server layers, has established SQL as the standard link between the application and database tiers. In the future, the role of SQL in the Internet will extend beyond web site architectures to include data management for collaborating applications and distributed objects in a web services architecture. 

Java Integration (JDBC)

A major area of SQL development over the last five to ten years has been the integration of SQL with Java. Seeing the need to link the Java language to existing relational databases, Sun Microsystems (the creator of Java) introduced Java Database Connectivity (JDBC), a standard API that allows Java programs to use SQL for database access. JDBC received a further boost when it was adopted as the data access standard within the Java2 Enterprise Edition (J2EE) specification, which defines the operating environment provided by all of the leading Internet application servers . In addition to its role as a programming language from which databases are used, many of the leading database vendors have also announced or implemented Java support within their database systems, allowing Java to be used as a language for stored procedures and business logic within the database itself. This trend toward integration between Java and SQL will insure the continued importance of SQL in the new era of Java-based programming.

Industry Infrastructure

Perhaps the most important factor contributing to the growing importance of SQL is the emergence of an entire computer industry infrastructure based on SQL. SQL-based relational database systems are an important part of this infrastructure. Enterprise applications that use SQL and require a SQL-based database are another important part, as are reporting tools, data-entry tools, design tools, programming tools, and a host of other tools that simplify the use of SQL. A large pool of experienced SQL programmers is a critical part of the infrastructure. Another important part is the training and support services that surround SQL and help to create and perpetuate SQL expertise. An entire subindustry has emerged around SQL consulting, optimization, and performance-tuning. All parts of this infrastructure tend to reinforce one another and contribute to the ongoing success of the other parts. Simply stated, to solve data management problems, the easiest, lowest-risk, lowest-cost solution is almost always a solution based on SQL.