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|- | |- | ||
|'<<' | |'<<' | ||
| | |subsumption qualifier used to indicate descendants or Self of against an identifier | ||
|<nowiki><<:sct:714628002|Prediabetes|</nowiki> | |<nowiki><<:sct:714628002|Prediabetes|</nowiki> | ||
means prediabetes or any of its descendants | means prediabetes or any of its descendants | ||
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The set of instances are either instances of a type , or members of a set, or an instance identifier. | The set of instances are either instances of a type , or members of a set, or an instance identifier. | ||
It has similar meaning to 'Select ID From TABLE ' in SQL but with the added convenience of simply indicating the source. | It has similar meaning to 'Select ID From TABLE ' in SQL but with the added convenience of simply indicating the source.<syntaxhighlight lang="actionscript3"> | ||
fromClause: 'from' from| booleanFrom ; | |||
from: { exclude? description (reference | fromClause |whereClause}; | |||
booleanFrom: from (and|or) from+; | |||
</syntaxhighlight>A from clause consists of a single from or boolean from, a single from consisting optional exclusion, description and has either a reference, a from clause, or where clause. | |||
Examples of use of from: | Examples of use of from: | ||
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|get me the the instances from the query (or set of) Patients with diabetes | |get me the the instances from the query (or set of) Patients with diabetes | ||
|- | |- | ||
| from {<<sct:763158003 | Medicinal product (product) | | |<nowiki> from { <<sct:763158003| Medicinal product (product) |} </nowiki> | ||
|<syntaxhighlight lang="json"> | |<syntaxhighlight lang="json"> | ||
{"from" : { | {"from" : { | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
|get me medicinal product concepts or subtypes of | |get me medicinal product concepts or subtypes of | ||
|- | |||
| <nowiki> from { @:Patient | |||
} | |||
and { ^im:PatientsRegisteredForGMS | |||
} | |||
</nowiki> | |||
|<syntaxhighlight lang="json"> | |||
{"from" : { | |||
"boolFrom" : "and", | |||
"from" : [ | |||
{"@id" : ":Patient" | |||
}, | |||
{ "@set" : "im:PatientsRegsteredForGMS" | |||
} | |||
] | |||
} | |||
} | |||
</syntaxhighlight> | |||
| get me things that are both patients and gms registered (note that as the gms registered ARE a set of patients, the patient type filter is not needed) | |||
|} | |||
=== Where clause === | |||
The where clause navigates the graph and filters properties and values from the set of instances identified in the from clause or a further filter on properties from a select clause. | |||
In effect it combines JOIN and WHERE and UNION from SQL with the additional ordering and limits from a subquery (SELECT) clause, which is ideal for representing "latest of" type clauses. | |||
Because the where clause supports ordering (in effect turning it into a subquery), a convenient THEN clause (itself a where clause) can be used to further test the results of a filtered, ordered, and limited set of records. This enables a more intuitive rule based approach than the equivalent correlated subquery that is needed in SQL e.g. get me patients whose latest blood pressure within the last 6 months is >150. | |||
Like SPARQL, the where clause can follow a property path and with nested boolean logic, enables highly granular filtering at leaf level without the need to bind aliases as in SQL e,g. where { home address where { post code starts with "YO18" } } |
Latest revision as of 13:07, 20 March 2023
These pages describe the IM Query grammar conventions and meaning.
A formal IMQ Grammar can be accessed in ABNF form at https://github.com/endeavourhealth-discovery/IMDirectory/blob/develop/im_library/src/antlr4/grammars/ECL.g4
The following is used as a working example throughout the pages:
Find:
Patients
Registered for GMS
Aged 65 to 70 or Diabetic
Latest systolic BP within the last 6 months is >150
Not followed by a screening invite
Not already hypertensive
Symbol conventions
A small set of symbols are used to represent meaningful language tokens. These are:
Symbol | Meaning | Example |
---|---|---|
'{' '}' | Used for clauses to differentiate the content from other similar clauses, as well as to indicate graph traversal. It is used in the same way as { } is used in Json to represent and object. | where {age >=65 to <75 units : years} |
',' | comma used to indicate a list entry number 2 or more. the language does not require brackets to show a list. | where { :concept in ^:VSET_Diabetes, <<:sct:714628002|Prediabetes } means that the concept is either a member of the Diabetes value set or is prediabetes or subtype of it |
' ( )' | used for method arguments such as units of measure | >18(years) to indicate that the number is qualified by a unit |
'@' | used as an identifier qualifier to indicate a type. | im:Concept
indicates that this refers to instances of type im:concept from { @:Patient} means that the query is looking for all instances of type patient. |
''^' | used as an identifier qualifier to indicate a set or population elsewhere defined | rom { ^ex:RegisteredPatients} means the set of registered patients, used mostly in referencing base populations or value /reference sets |
'<<' | subsumption qualifier used to indicate descendants or Self of against an identifier | <<:sct:714628002|Prediabetes|
means prediabetes or any of its descendants |
'<' | used to indicate 'descendants of but not including self' | <:sct:714628002|Prediabetes|
means any of its descendants but not prediabetes itself * (rarely used) |
'>>' | ed to indicate 'Ancestors of including self; against an identifier . | from {>>sct:127489000| has active ingredients
means the property active ingredients or any of its super properties. Used to validate attributes in the domain range Snomed concept model. |
''|' '|' | used as a short cut to indicate the name of a concept or | :sct:714628002|Prediabetes| |
Identifiers
Query definitions include reference to a data model types, properties, concepts or sets. Identifiers are represented as RDF IRIs in both the full or prefixed form. For example:
http://snomed.info/sct# and sct: 29857009 may be equivalent where the query contains a prefix list
Boolean operators
The boolean operators 'and' , 'or' can operate in either the from or where clause, using a "bool" predicate. 'and' is the same as an intersection (all must be true), or is a union (at least one true).
Exclude is the negation operator that negates a clause and all of its sub clauses.
Example use of boolean operators in where clause:
Plain | Json |
---|---|
where {
{:age>= 18 (years) } and {:statedGender is :905031000252103|Male|} } |
{"where" : {
"bool" : "and",
"where" : [ { "@id" : ":age",
"operator" : ">=",
"value" : 18,
"unit" : "yeara"},
{"@id" : ":statedGender",
"in" : [ {"@id" : "im:905031000252103",
"name" : "Male (stated gender)" } ] } ] }
|
From Clause
The from clause means "get me a instances of....", returning a set of identifiers of object instances.
The set of instances are either instances of a type , or members of a set, or an instance identifier.
It has similar meaning to 'Select ID From TABLE ' in SQL but with the added convenience of simply indicating the source.
fromClause: 'from' from| booleanFrom ;
from: { exclude? description (reference | fromClause |whereClause};
booleanFrom: from (and|or) from+;
A from clause consists of a single from or boolean from, a single from consisting optional exclusion, description and has either a reference, a from clause, or where clause.
Examples of use of from:
Plain | Json | |
---|---|---|
from { @:Patient } | {"from" : {
"@type" : ":Patient"}
}
|
get me instances of type patient |
from {^myQuery:PatientsWithdiabetes} | {"from" : {
"@set" : "muQuery:PatientsWithDiabetes"}
}
|
get me the the instances from the query (or set of) Patients with diabetes |
from { <<sct:763158003| Medicinal product (product) |} | {"from" : {
"@id" : "sct:763158003",
"name" : "Medicinal product (product)",
"descendantsOrSelfOf" : true}
}
|
get me medicinal product concepts or subtypes of |
from { @:Patient } and { ^im:PatientsRegisteredForGMS } | {"from" : {
"boolFrom" : "and",
"from" : [
{"@id" : ":Patient"
},
{ "@set" : "im:PatientsRegsteredForGMS"
}
]
}
}
|
get me things that are both patients and gms registered (note that as the gms registered ARE a set of patients, the patient type filter is not needed) |
Where clause
The where clause navigates the graph and filters properties and values from the set of instances identified in the from clause or a further filter on properties from a select clause.
In effect it combines JOIN and WHERE and UNION from SQL with the additional ordering and limits from a subquery (SELECT) clause, which is ideal for representing "latest of" type clauses.
Because the where clause supports ordering (in effect turning it into a subquery), a convenient THEN clause (itself a where clause) can be used to further test the results of a filtered, ordered, and limited set of records. This enables a more intuitive rule based approach than the equivalent correlated subquery that is needed in SQL e.g. get me patients whose latest blood pressure within the last 6 months is >150.
Like SPARQL, the where clause can follow a property path and with nested boolean logic, enables highly granular filtering at leaf level without the need to bind aliases as in SQL e,g. where { home address where { post code starts with "YO18" } }