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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 |
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Operators
AND | ANDOR | DIV | IN |
LIKE | MOD | NOT | OR |
XOR |
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Built-in constants
? | SELF | CONST_E | PI |
FALSE | TRUE | UNKNOWN |
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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 |
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Built-in procedures
INSERT | REMOVE |
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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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