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Oracle Database provides information about all of the tables, views, columns, and procedures in a database. This information about information is known as metadata. [1] It is stored in two locations: data dictionary tables (accessed via built-in views) and a metadata registry.
The constructor and methods of an Abstract Data Type are written in PL/SQL. The resulting Abstract Data Type can operate as an object class in PL/SQL. Such objects can also persist as column values in Oracle database tables. PL/SQL is fundamentally distinct from Transact-SQL, despite superficial similarities.
The query retrieves all rows from the Book table in which the price column contains a value greater than 100.00. The result is sorted in ascending order by title. The asterisk (*) in the select list indicates that all columns of the Book table should be included in the result set.
The DUAL table is a special one-row, one-column table present by default in Oracle and other database installations. In Oracle, the table has a single VARCHAR2(1) column called DUMMY that has a value of 'X'. It is suitable for use in selecting a pseudo column such as SYSDATE or USER.
Oracle Corporation introduced Oracle ConText first as a software option, then as an Oracle data cartridge (a server-based software module) for text retrieval when it released version 8 of the Oracle database in 1997. It used the default schema CTXSYS and the default tablespace DRSYS.
Individual columns in a row are retrieved either by name or by column number. There may be any number of rows in the result set. The row result set has metadata that describes the names of the columns and their types. There is an extension to the basic JDBC API in the javax.sql.
However, in some database systems, it is allowed to use correlated subqueries while joining in the FROM clause, referencing the tables listed before the join using a specified keyword, producing a number of rows in the correlated subquery and joining it to the table on the left.
The PHONE_NUMBER table also contains a foreign key column, "CONTACT_ID", which holds the unique ID number assigned to the contact when it was created. In order to recreate the original contact, the database engine uses the foreign keys to look for the related items across the group of tables and reconstruct the original data.