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The following is a list of the EXPRESS language keywords.

Abstract

AGGREGATE

ALIAS

ARRAY

AS

BAG

BEGIN

BINARY

BOOLEAN

BY

CASE

CONSTANT

CONTEXT

DERIVE

ELSE

END

END_ALIAS

END_CASE

END_CONSTANT

END_CONTEXT

END_ENTITY

END_FUNCTION

END_IF

END_LOCAL

END_MODEL

END_PROCEDURE

END_REPEAT

END_RULE

END_SCHEMA

END_TYPE

ENTITY

ENUMERATION

ESCAPE

FIXED

FOR

FROM

FUNCTION

GENERIC

IF

INTEGER

INVERSE

LIST

LOCAL

LOGICAL

MODEL

NUMBER

OF

ONEOF

OPTIONAL

OTHERWISE

PROCEDURE

QUERY

REAL

REFERENCE

REPEAT

RETURN

RULE

SCHEMA

SELECT

SET

SKIP

STRING

SUBTYPE

SUPERTYPE

THEN

TO

TYPE

UNIQUE

UNTIL

USE

VAR

WHERE

WHILE

 

 

 

Operators

AND

ANDOR

DIV

IN

LIKE

MOD

NOT

OR

XOR

 

 

 

Built-in constants

?

SELF

CONST_E

PI

FALSE

TRUE

UNKNOWN

 

Built-in functions

ABS

ACOS

ASIN

ATAN

BLENGTH

COS

EXISTS

EXP

FORMAT

HIBOUND

HIINDEX

LENGTH

LOBOUND

LOG

LOG2

LOG10

LOINDEX

NVL

ODD

ROLESOF

SIN

SIZEOF

SQRT

TAN

TYPEOF

USEDIN

VALUE

VALUE_IN

VALUE_UNIQUE

 

 

 

Built-in procedures

INSERT

REMOVE

 

 

Data Types

EXPRESS data types are classified under the following classes:

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EXPRESS supports the following simple data types:

NUMBER

Its domain includes all numeric values in the EXPRESS language.

REAL

Its domain includes all rational, irrational and scientific real numbers.

INTEGER

Its domain includes all rational numbers.

LOGICAL

Its domain includes three literals TRUE, FALSE and UNKNOWN.

BOOLEAN

Its domain includes two literals TRUE and FALSE.

STRING

Its domain includes sequences of characters. The characters that are permitted to form part of a string value are defined in ISO 10646.

BINARY

Its domain includes sequences of bits, which are represented by the characters 0 or 1.


Jotnes Express compiler accepts some additional data type when the EDM_EXPRESS_EXTENSION option is switched on.

_FILE

A file that is imported from the file system and stored as database file

_BLOB

A binary large object stored within data space of an databased instance

_SEQUENCENUMBER

A sequence number within an entity extent (assigned automatically)

_INDEX

An index within an entity extent (assigned automatically)

_NAME

A string that obeys the conventions of a simple id

_TIMESTAMP

Automatically assigned timestamp

_DATETIME

Manullay assigned data and time


EXPRESS supports the following aggregate data types:

ARRAY

It has as its domain indexed, fixed-size collection of like elements.

LIST

Its domain includes sequences of like elements.

BAG

Its domain includes unordered collections of like elements.

SET

Its domain includes unordered


collections of like elements. It is a specialization of the BAG data type but the collection shall not contain two or more instance equals.

EXPRESS supports two classes of named data types:

ENTITY

An entity data type is established by ENTITY declarations. An entity data type is assigned an identifier that can be referenced by a defined data type or an attribute of another entity data type.

TYPE

A defined data type is established by TYPE declarations. A defined data type is assigned an identifier that can be referenced by a defined data type or an attribute of an entity data type.

There are two classes of constructed data types: ENUMERATION data type and SELECT data type.

ENUMERATION

An ENUMERATION data type has as its domain an ordered set of names. The names represent the values of the enumeration data type.

SELECT

The SELECT data type has as its domain a list of identifier of named data types. A SELECT data type is a limited form of generalization of each of the named data types in its list. Members of a SELECT list do not have to have common attributes.

There are two main classes of generalized data types: AGGREGATE data type and GENERIC data type.

AGGREGATE

An AGGREGATE data type is a generalization of all aggregate data types (ARRAY, LIST, BAG and SET). This data type is used only to represent generalized functional and procedural parameters.

GENERIC

A GENERIC data type is a generalization of all data types. This data type is used to represent generalized functional and procedural parameters, and/or generalized types of elements in an aggregate data type.

 

Entities

EXPRESS is used to define entities. Within the entity definition, all the attributes and behaviors which characterize it are declared. An entity is declared by the keyword ENTITY and terminated by the keyword END_ENTITY.

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