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Oracle Corporation calls these variables "substitution variables". Programmers can use them anywhere in a SQL or PL/SQL statement or in SQL Plus commands. They can be populated by a literal using DEFINE or from the database using the column command. predefined variables, prefixed with an underscore ('_') [10]
Implementations from version 8 of Oracle Database onwards have included features associated with object-orientation. One can create PL/SQL units such as procedures, functions, packages, types, and triggers, which are stored in the database for reuse by applications that use any of the Oracle Database programmatic interfaces.
This is an important element of SQL. Statements, which may have a persistent effect on schemata and data, or may control transactions, program flow, connections, sessions, or diagnostics. SQL statements also include the semicolon (";") statement terminator. Though not required on every platform, it is defined as a standard part of the SQL grammar.
Starting with version 2.0, PostGIS embeds raster support for 2-D rasters; a special function offers declarative raster query functionality. SciQL is an array query language being added to the MonetDB DBMS. SciDB is a more recent initiative to establish array database support. Like SciQL, arrays are seen as an equivalent to tables, rather than a ...
Major DBMSs, including SQLite, [5] MySQL, [6] Oracle, [7] IBM Db2, [8] Microsoft SQL Server [9] and PostgreSQL [10] support prepared statements. Prepared statements are normally executed through a non-SQL binary protocol for efficiency and protection from SQL injection, but with some DBMSs such as MySQL prepared statements are also available using a SQL syntax for debugging purposes.
A variation of example 3 allows "Dynamic SQL" to be created in the source code, and then used to communicate with Rdb via a structure known as SQLDA (SQL Descriptor Area). On OpenVMS systems, Oracle Rdb is a popular (although expensive) upgrade path for applications written using Record Management Services (RMS) files.
A SELECT statement retrieves zero or more rows from one or more database tables or database views. In most applications, SELECT is the most commonly used data manipulation language (DML) command. As SQL is a declarative programming language, SELECT queries specify a result set, but do not specify how to calculate it.
The values of database columns are set only by a SQL “select” statement; no other command can change their values. SQR has an array data structure. An array has one or more fields, each of one of the available types. Each field may have multiple occurrences, giving SQR the equivalent of two-dimensional arrays.