JQL (JIRA Query Language) Cheat Sheet - Cheatography 19/12/2017 · A function in JQL appears as a word followed by parent­heses, which may contain one or more explicit values or Jira fields. A function performs a calcul­ation on either specific Jira data or the function's content in parent­heses, such that only true results are retrieved by the function, and then again by the clause in which the function is used.