Data Composition System Expression Language
The data composition system expression language is intended to create expressions used throughout the system.
Expressions are used in the following subsystems:
- data composition schema – to describe calculated fields, total fields, link expressions, etc;
- data composition settings – to describe custom field expressions;
- data composition template – to describe data set link expressions, template parameter descriptions, etc.
An expression can contain literal constants. Literal constants can be as follows:
String literal is enclosed in double quotation marks ("), e.g.:
If you need to use double quotation marks within a string literal, use two double quotation marks.
"Literal""in quotation marks"""
A number is written without spaces, in decimal format. Its fractional part is separated by a period ("."). Example:
A date literal is written using the DATETIME key literal. This keyword is followed by a year, month, day, hours, minutes, and seconds separated by commas. Specifying time is not mandatory.
DATETIME(1975, 1, 06) – January the sixth, 1975
DATETIME(2006, 12, 2, 23, 56, 57) – The Second of December, 2006, 23 h 56 m 57 s
Boolean values can be written using True and False literals.
A literal follows the Type keyword after which the name of type is written in brackets.
To specify literals of other types (system enumerations, preset data), use the Value keyword followed by the literal name in brackets.
Operations with Numbers
Operations with Rows
Rules for Comparing Two Values
Working with NULL Value
Mechanism of Properties (Characteristics) and Categories
Bilingual Presentation of Data Composition System Keywords