ERD

erDiagram
  clinical_code {
    emis_code_id VARCHAR PK
    snomed_concept_id VARCHAR FK
    snomed_description_id VARCHAR FK
    parent_emis_code_id VARCHAR FK
  }

  snomed_concept {
    snomed_concept_id VARCHAR PK
  }

  snomed_description {
    snomed_description_id VARCHAR PK
  }

  clinical_code }|--|{ clinical_code : "parent_code"
  clinical_code }|--|{ snomed_concept : "maps_to_concept"
  clinical_code }|--|{ snomed_description : "has_description"