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Xeround originally targeted its database for telecom applications that process subscriber data, such as the databases that track the locations and capabilities of mobile telephones in a network. More recently, the company has repackaged its database as IDG Core and supplemented it with two additional products IDG Unify, which federates data across existing databases for access via IDG, and IDG Sync, which synchronizes data across databases. With these additions, the company now positions IDG as a database virtualization solution, providing a single view across disparate databases and networks.

he ANSI/ISO SQL standard specifies the syntax of the SQL language using a formal Backus Naur Form (BNF) notation. Unfortunately, the standard is difficult to read and understand for several reasons. First, the standard specifies the language bottom-up rather than top-down, making it difficult to get the big picture of a SQL statement. Second, the standard uses unfamiliar terms (such as table-expression and predicate). Finally, the BNF in the standard is many layers deep, providing a very precise specification but masking the relatively simple structure of the SQL language. This appendix presents a complete, simplified BNF for standard SQL as it is commonly implemented in the products of most DBMS vendors. Specifically: The language described generally conforms to that required for entry-level conformance to the SQL standard, plus those intermediate-level and full-level conformance features that are commonly found in the major DBMS products. The module language is omitted because it is replaced in virtually all SQL implementations by embedded SQL or by a SQL API. Components of the language are referred to by the common names generally used in DBMS vendor documentation, rather than by the technical names used in the standard. The BNF in this appendix uses the following conventions: SQL keywords appear in all UPPERCASE MONOSPACE characters. Syntax elements are specified in italics. The notation element-list indicates an element or a list of elements separated by commas. Vertical bars (|) indicate a choice between two or more alternative syntax elements. Square brackets ([ ]) indicate an optional syntax element enclosed within them. Braces ({ }) indicate a choice among required syntax elements enclosed within them.

Part VII:

These statements define the structure of a database, including its tables and views and the DBMS-specific objects that it contains:

CREATE TABLE table ( table-def-item-list ) DROP TABLE table [ drop-options ] CREATE VIEW view [ ( column-list ) ] AS query-spec [ WITH CHECK OPTION ] DROP VIEW view [ drop-options ] CREATE db-object-type db-object-name [ db-object-spec ] DROP db-object-type db-object-name [ drop-options ] ALTER db-object-type db-object-name alter-action

The keywords used to specify database objects (db-object-type) depend on the specific DBMS. Typical database objects with associated privileges include TABLE, VIEW, SCHEMA, PROCEDURE, FUNCTION, TRIGGER, DOMAIN, INDEX, and the named storage areas maintained by the DBMS. The SQL syntax used to specify these objects is specific to the DBMS that supports them. The specific alter actions supported are also DBMS-specific and object type specific. The language elements used in the CREATE, DROP, and ALTER, statements are

Language Element table-def-item column-definition Syntax column-definition | table-constraint column data-type [ DEFAULT { literal | USER | NULL } ] [ column-constraint-list ] [ CONSTRAINT constraint-name ] { NOT NULL | uniqueness | foreign-key-ref | check-constr } [ constraint-timing ] [ CONSTRAINT constraint-name ] { uniqueness | foreign-key-constr | check-constr } [ constraint-timing ] UNIQUE ( col-list ) | PRIMARY KEY ( col-list ) FOREIGN KEY ( col-list ) foreign-key-ref REFERENCES table [ ( col-list ) ] [ MATCH { FULL | PARTIAL } ] [ ON DELETE ref-action ] CASCADE | SET NULL | SET DEFAULT | NO ACTION CHECK ( search-condition ) [ INITIALLY IMMEDIATE | INITIALLY DEFERRED ] [ [ NOT ] DEFERRABLE ] CASCADE | RESTRICT