QGIS/resources/function_help/json/nullif

{
  "name": "nullif",
  "type": "function",
  "groups": ["Conditionals"],
  "description": "Returns a NULL value if value1 equals value2; otherwise it returns value1. This can be used to conditionally substitute values with NULL.",
  "arguments": [{
    "arg": "value1",
    "description": "The value that should either be used or substituted with NULL."
  }, {
    "arg": "value2",
    "description": "The control value that will trigger the NULL substitution."
  }],
  "examples": [{
    "expression": "nullif('(none)', '(none)')",
    "returns": "NULL"
  }, {
    "expression": "nullif('text', '(none)')",
    "returns": "'text'"
  }, {
    "expression": "nullif(\"name\", '')",
    "returns": "NULL, if name is an empty string (or already NULL), the name in any other case."
  }],
  "tags": ["substitute", "equals", "condition", "compare"]
}