"full outer join" meaning in English

{
  "etymology_text": ": full outer join < → δείτε τις λέξεις full, outer και join",
  "forms": [
    {
      "form": "full outer join"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "left outer join"
    },
    {
      "word": "right outer join"
    }
  ],
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Βάσεις δεδομένων (αγγλικά)",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "The result set of the full outer join has NULL values for every column of the table that does not have a matching row in the other table."
        }
      ],
      "glosses": [
        ", (στη σχεσιακή άλγεβρα) η πλήρης εξωτερική συνένωση"
      ],
      "id": "el-full_outer_join-en-noun-0uKDP5EI",
      "raw_tags": [
        "βάσεις δεδομένων"
      ]
    }
  ],
  "word": "full outer join"
}

{
  "etymology_text": ": full outer join < → δείτε τις λέξεις full, outer και join",
  "forms": [
    {
      "form": "full outer join"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "left outer join"
    },
    {
      "word": "right outer join"
    }
  ],
  "senses": [
    {
      "categories": [
        "Βάσεις δεδομένων (αγγλικά)"
      ],
      "examples": [
        {
          "text": "The result set of the full outer join has NULL values for every column of the table that does not have a matching row in the other table."
        }
      ],
      "glosses": [
        ", (στη σχεσιακή άλγεβρα) η πλήρης εξωτερική συνένωση"
      ],
      "raw_tags": [
        "βάσεις δεδομένων"
      ]
    }
  ],
  "word": "full outer join"
}