In this section, we illustrate how filters can be applied to a set of reference set members to restrict the matching values.

Overview

Member filters provide the ability to filter the rows of a reference set, based on the value of specific fields in the reference set. These filters are specified inside double curly braces, and begin with the letter "M".

Member Filters

To apply a member filter to one or more reference sets, the fields of those reference sets are matched against specified criteria. Only reference set members whose field values match the given criteria will be included in the results.

For example, the following expression constraint will match all referencedComponentIds (i.e. SNOMED CT concept id) from the active 447562003 | ICD-10 complex map reference set| rows, which map to the ICD-10 code "J45.9" (as a word prefix). When applied to the July 2021 international edition, this will match 59 concepts, including 195967001 | Asthma| , 707447008 | Exacerbation of severe persistent asthma (disorder)| and 401193004 | Asthma confirmed (situation)| .

^ 447562003 |ICD-10 complex map reference set| {{ M mapTarget = "J45.9" }}

Please note that by default, a word-prefix-any-order match is performed. Therefore the following expression constraint will match on rows that have a mapTarget of "J45.0", "J45.1",..., "J45.8", "J45.9" etc.

^ 447562003 |ICD-10 complex map reference set| {{ M mapTarget = "J45" }}

To ensure an exact string match is performed, a wildcard search (without an '*') is required. For example, the expression constraint below will only match rows that have a mapTarget of "J45.9".

^ 447562003 |ICD-10 complex map reference set| {{ M mapTarget = wild:"J45.9" }}

Multiple field constraints can be applied within a reference set member filter. For example, the following expression constraint will return the referencedComponentId from the 447562003 | ICD-10 complex map reference set| rows, which have a mapGroup of "2", a mapPriority of "1" and a mapTarget of "J45.9".

^ 447562003 |ICD-10 complex map reference set| {{ M mapGroup = #2, mapPriority = #1, mapTarget = "J45.9" }}

Other comparison operators may also be used, when defining field criteria. The available operators depend on the field's datatype, as shown in the table below.

Data type	Comparison Operators
Data type	Brief syntax	Long syntax
SCTID / Expression	= , !=	= , != , NOT = , <>
Integer / Decimal	= , != , <= , < , >= , >	= , != , NOT = , <> , <= , < , >= , >
String	= , !=	= , != , NOT = , <>
Boolean	= , !=	= , != , NOT = , <>
Time	= , != , <= , < , >= , >	= , != , NOT = , <> , <= , < , >= , >

In addition, reference set fields of type 'string' may be filtered using the same word-prefix-any-order and wildcard techniques used by the description term filters. For example, the following expression constraint will match all referencedComponentId from the active 447562003 | ICD-10 complex map reference set| rows that have a mapGroup not equal to 2, a mapPriority less than 2, and a mapTarget that starts with the letter "J".

^ 447562003 |ICD-10 complex map reference set| {{ M mapGroup != #2, mapPriority < #2, mapTarget = wild:"J*" }}

Member filters can also be used in combination with the memberOf function to support the selection of other fields of a reference set (see 6.1 Simple Expression Constraints). For example, the following expression constraint returns the active SNOMED CT concept that is considered to be the same as the inactive concept 67415000 | Hay asthma|

^ [targetComponentId] 900000000000527005 |SAME AS association reference set| {{ M referencedComponentId = 67415000 |Hay asthma| }}

For more information on the use of reference set field names in ECL, please refer to Appendix E - Reference Set Fields.

For additional ways of specifying queries over the historical association reference sets, please refer to 6.11 History Supplements.

Search

6.10 Member Filters

Overview

Member Filters