Tracker Query Expression Syntax

In order to work effectively with the Query Expression Editor it is important to have a working knowledge of TADB structure and Basic Tracker and vocabulary.

Rules for building Query expressions include:

	Syntax conventions used for building queries.
	Methods in the expression language.
	Simple non-terminals.
	Complex non-terminals.
	Named expressions.

Syntax conventions used for building queries

The syntax conventions use different font attributes for different components of the syntax.

Syntax	Applied to	Definitions
Italic	Non-terminals.	Placeholders in the syntax and are defined elsewhere in this syntax summary.
Bold	Terminals	Literal reserved words and symbols that must be entered as shown. Characters are always case sensitive, except for NULL, which can be any possible case combination.
opt	Optional	Non-terminals followed by _opt are always optional. Example { expression _opt } Indicates an optional expression enclosed in curly braces.
Default typeface	Terminal characters	Characters be used as terminals in expressions.

Note: Alternative definitions are listed on separate lines, except when prefaced with the words one of.

Methods in the expression language

The three methods that use the expression language are:

Method	Definition
GetValues(ItemID,AttributeList)	Retrieve a set of values from a particular item's attributes.
ListItems(ItemType,Expression)	Find out if a particular item does or does not meet a set of criteria.
TestItem(ItemID,Expression)	Find all the items that do match a set of criteria.

Start Symbols

The basic building blocks that will make an expression valid are the start symbols, attribute-list and expression.

Non-terminal	Definition
(Start Symbols)
attribute-list	list-attribute attribute-list ; list-attribute Note: A complete attribute-list symbol must be passed to GetValues.
expression	term ! _opt ( expression ) expression & expression expression \| expression type-id { expression } Note: A complete expression symbol must be passed to TestItem or ListItems.

Simple non-terminals

Simple non-terminals can be combined to form more complex non-terminals.

Non-terminal	Definition
Attribute-id	Identifier
Digit	One of 0 1 2 3 45 6 7 8 9
Group-id	Identifier
Length	Number
Letter	One of _ a b c d e f g h i j k l m n o p q r s t u v w x y z A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Named-expression-name	Identifier
Number	Digit, e.g. 5 Number digit, e.g. 25
Relational	One of = < > <= >= =l =r
Space	A single blank space character
Start-pos	Number
Text	Depends on the: Operator that precedes the text and Data type of the attribute being compared. Will elicit one of the following results. The text will be converted to the correct type automatically. When either of the following operators are used: =l =r the target attribute will be converted to character form before comparison. If a type conversion cannot take place, an error condition will result and the query will not execute.
	Timestamp literals can take one of two forms.
	Absolute time stamps	‘yyyy-mo-dd[ hh:mi:ss]'.
		yyyy	4 digit year
		mo	2 digit month
		dd	2 digit date
		hh	hours
		mi	minutes
		ss	seconds
	Relative time stamps	‘M:Q’.
		M	Measurement unit, which is one of the following:
			yy	years
			q	quarters
			m	months
			d	days
			ww	weeks
			h	hours
			n	minutes
			s	seconds
			ms	milliseconds
		Q	An integer quantity of time from the current time in specified measurement units. Negative numbers are used to represent previous time stamps.
Type-id	Identifier
Value	Either: ‘ text ‘ null min() max()
minmax	.min( identifier ) .max( identifier )

Complex non-terminals

Complex definitions usually have more than one rule.

Non-terminals	Definition
attribute	group-id . attribute-id start-pos _opt length _opt
identifier	letter digit identifier letter identifier digit identifier space identifier
list-attribute	attribute group-id (sub-expression) minmax_opt.attribute-id start-pos_opt length_opt type-id { list-attribute }
sub-attribute	attribute-id start-pos _opt length _opt
sub-expression	sub-term sub-expression & sub-expression sub-expression \| sub-expression
sub-term	! _opt attribute Relational values ! _opt sub-attribute Relational values
term	! _opt attribute Relational values ! _opt group-id (sub-expression ) minmax_opt
values	value values, value

Named expressions

A named expression may be a single symbol or multiple symbols and may not contain a text symbol except in the context of completing a value symbol.

The syntax for using a named expression is:

$ named-expression-symbol $

A named expression can be inserted anywhere except between ‘ characters.

More information

About the Query engine.