Extended Syntax

MogDB provides extended syntax .

Table 1 Extended SQL syntax

Category	Keywords	Description
Creating a table (CREATE TABLE)	INHERITS ( parent_table [, … ] )	Specifies whether an inherited table is supported.
table_constraint: EXCLUDE USING index_method index_parameters [ WHERE ( predicate ) ] | FOREIGN KEY ( column_name [, … ] ) REFERENCES reftable [ ( refcolumn [, … ] ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE action ] [ ON UPDATE action ]	Specifies that users cannot use EXCLUDE USING index_method to create an excluding constraint for a table.
Altering a table (ALTER TABLE)	TO { GROUP groupname | NODE ( nodename [, … ] ) }	Modifies the list of DNs where table data is distributed.
DELETE NODE ( nodename [, … ] )	Deletes the DNs on which table data is distributed.
Loading a module	CREATE EXTENSION	Loads a new module (such as DBLINK) to the current database.
ALTER EXTENSION	Modifies the loaded module.
DROP EXTENSION	Deletes the loaded module.
Aggregate functions	CREATE AGGREGATE	Defines a new aggregate function.
ALTER AGGREGATE	Modifies the definition of an aggregate function.
DROP AGGREGATE	Drops an existing aggregate function.
Operators	CREATE OPERATOR	Defines a new operator.
ALTER OPERATOR	Modifies the definition of an operator.
DROP OPERATOR	Drops an existing operator from the database.
Operator classes	CREATE OPERATOR CLASS	Defines a new operator class.
ALTER OPERATOR CLASS	Modifies the definition of an operator class.
DROP OPERATOR CLASS	Drops an existing operator class.
Operator families	CREATE OPERATOR FAMILY	Defines a new operator family.
ALTER OPERATOR FAMILY	Modifies the definition of an operator family.
DROP OPERATOR FAMILY	Deletes an existing operator family.
Text search parsers	CREATE TEXT SEARCH PARSER	Creates a text search parser.
ALTER TEXT SEARCH PARSER	Modifies a text search parser.
DROP TEXT SEARCH PARSER	Deletes an existing text search parser.
Text search templates	CREATE TEXT SEARCH TEMPLATE	Creates a text search template.
ALTER TEXT SEARCH TEMPLATE	Modifies a text search template.
DROP TEXT SEARCH TEMPLATE	Deletes an existing text search template.
Collation rules	CREATE COLLATION	Creates a collation rule. The collation rule allows users to define data in the column-level, or even the collation rule and character class behaviors at the operation level.
ALTER COLLATION	Modifies a collation rule.
DROP COLLATION	Deletes a collation rule.
Generating a notification	NOTIFY	The NOTIFY command sends a notification together with an optional "payload" string to each client that has previously executed LISTEN for a specified channel in the current database.
Listening for a notification	LISTEN	Registers a listener for the current session.
Stopping listening for a notification	UNLISTEN	Clears all listeners of this session registration.
Loading or reloading a shared library file	LOAD	Loads a shared library file to the address space of the database server.
Releasing session resources in a database	DISCARD	Releases session resources in a database.
Procedural languages	CREATE LANGUAGE	Registers a new language.
ALTER LANGUAGE	Modifies the definition of a procedural language.
DROP LANGUAGE	Deletes a procedural language.
Domains	CREATE DOMAIN	Creates a domain.
ALTER DOMAIN	Modifies the definition of an existing domain.
DROP DOMAIN	Deletes a domain.
Code conversion	CREATE CONVERSION	Defines the character set conversion.
ALTER CONVERSION	Modifies the definition of a code conversion.
DROP CONVERSION	Deletes a previously defined code conversion.
Type conversion	CREATE CAST	Defines a new type conversion. A conversion specifies how to perform a conversion between two data types.
DROP CAST	Deletes a previously defined type conversion.
Creating a cursor	CURSOR name [ BINARY ] [ INSENSITIVE ] [ [ NO ] SCROLL ] [ WITH HOLD ] FOR query	INSENSITIVE is used only for being compatible with the SQL standard. SCROLL declares that the cursor can be used for reverse search. WITH HOLD indicates that a cursor can still be used after the transaction creating the cursor is successfully committed.
Moving a cursor	MOVE BACKWARD	A reverse mobile cursor can be used only when it is used together with SCROLL.