> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/implementation-guides/loinc-implementation-guide/technical-application/6.4-using-the-loinc-ontology/6.4.3-accessing-the-reference-set-in-a-relational-database.md). # Accessing the Reference Set in a Relational Database If the LOINC Ontology has been loaded in a relational database using a model that complies with the RF2 specification for tables and column names, the content can be accessed using SQL queries in line with the examples below. To Set up SNOMED CT in a relational database, please follow the guidance and instructions provided in the [SQL Practical Guide](https://docs.snomed.org/snomed-ct-practical-guides/snomed-ct-sql-practical-guide/). ## SQL Examples
Service NameSQL QueryResult

Get all members of the reference set

The reference set used in this example is:

635111010000100 |Logical Observation Identifiers Names and Codes Orderable Reference Set (foundation metadata concept)|

SELECT referencedComponentId FROM snap_refset_simple WHERE active=1 AND refsetId=[refsetId];

for example

SELECT referencedComponentId FROM snap_refset_simple WHERE active=1 AND refsetId=635111010000100;
Returns the ids of all the concepts or descriptions that are the members of the reference set.

Test if a concept is a member of the reference set

The concept used in this example is:
141951010000102 |Mass concentration of neopterin in urine at point in time (observable entity)|

SELECT count(referencedComponentId) FROM snap_refset_simple WHERE active=1 AND refsetId=[refsetId] AND referencedComponentId=[candidateComponentId];

for example

SELECT count(referencedComponentId) FROM snap_refset_simple WHERE active=1 AND refsetId=635111010000100 AND referencedComponentId=141951010000102;


Returns:

  • 0 : if the candidate component is not in the reference set.

  • 1 : If the candidate component is a member of the reference set

    • Some types or reference set can include the same component more than once, so any value greater than zero indicate the component is a member of the references set.
Provide Feedback --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.snomed.org/implementation-guides/loinc-implementation-guide/technical-application/6.4-using-the-loinc-ontology/6.4.3-accessing-the-reference-set-in-a-relational-database.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.