"inner join" meaning in English

{
  "antonyms": [
    {
      "word": "outer join"
    }
  ],
  "etymology_text": ": inner join <→ δείτε τις λέξεις inner και join",
  "forms": [
    {
      "form": "inner join"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Βάσεις δεδομένων (αγγλικά)",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "η εσωτερική συνένωση"
      ],
      "id": "el-inner_join-en-noun-JymAijBp",
      "raw_tags": [
        "βάσεις δεδομένων"
      ]
    }
  ],
  "word": "inner join"
}

{
  "antonyms": [
    {
      "word": "outer join"
    }
  ],
  "etymology_text": ": inner join <→ δείτε τις λέξεις inner και join",
  "forms": [
    {
      "form": "inner join"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Βάσεις δεδομένων (αγγλικά)"
      ],
      "glosses": [
        "η εσωτερική συνένωση"
      ],
      "raw_tags": [
        "βάσεις δεδομένων"
      ]
    }
  ],
  "word": "inner join"
}