Oracle strives to comply with industry-accepted standards and participates actively in SQL standards committees. Industry-accepted committees are the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO), which is affiliated with the International Electrotechnical Commission (IEC). Both ANSI and the ISO/IEC have accepted SQL as the standard language for relational databases. When a new SQL standard is simultaneously published by these organizations, the names of the standards conform to conventions used by the organization, but the standards are technically identical.
The latest SQL standard was adopted in July 2003 and is often called SQL:2003. One part of the SQL standard, Part 14, SQL/XML (ISO/IEC 9075-14) was revised in 2006 and is often referenced as “SQL/XML:2006”. The formal names of this standard, with the exception of SQL/XML, are:
- ANSI/ISO/IEC 9075:2003, “Database Language SQL”, Parts 1 (“SQL/Framework”), 2 (“SQL/Foundation”), 3 (“SQL/CLI”), 4 (“SQL/PSM”), 9 (“SQL/MED”), 10 (“SQL/OLB”), 11(“SQL/Schemata”), and 13 (“SQL/JRT”)
- ISO/IEC 9075:2003, “Database Language SQL”, Parts 1 (“SQL/Framework”), 2 (“SQL/Foundation”), 3 (“SQL/CLI”), 4 (“SQL/PSM”), 9 (“SQL/MED”), 10 (“SQL/OLB”), 11(“SQL/Schemata”), and 13 (“SQL/JRT”).
The strengths of SQL provide benefits for all types of users, including application programmers, database administrators, managers, and end users. Technically speaking, SQL is a data sublanguage. The purpose of SQL is to provide an interface to a relational database such as Oracle Database, and all SQL statements are instructions to the database. In this SQL differs from general-purpose programming languages like C and BASIC. Among the features of SQL are the following:
- It processes sets of data as groups rather than as individual units.
- It provides automatic navigation to the data.
- It uses statements that are complex and powerful individually, and that therefore stand alone. Flow-control statements were not part of SQL originally, but they are found in the recently accepted optional part of SQL, ISO/IEC 9075-5: 1996. Flow-control statements are commonly known as “persistent stored modules” (PSM), and the PL/SQL extension to Oracle SQL is similar to PSM.
SQL lets you work with data at the logical level. You need to be concerned with the implementation details only when you want to manipulate the data. For example, to retrieve a set of rows from a table, you define a condition used to filter the rows. All rows satisfying the condition are retrieved in a single step and can be passed as a unit to the user, to another SQL statement, or to an application. You need not deal with the rows one by one, nor do you have to worry about how they are physically stored or retrieved. All SQL statements use the optimizer, a part of Oracle Database that determines the most efficient means of accessing the specified data. Oracle also provides techniques that you can use to make the optimizer perform its job better.
SQL provides statements for a variety of tasks, including:
- Querying data
- Inserting, updating, and deleting rows in a table
- Creating, replacing, altering, and dropping objects
- Controlling access to the database and its objects
- Guaranteeing database consistency and integrity
SQL unifies all of the preceding tasks in one consistent language.