{"type":"rich","version":"1.0","author_url":"https://blog.hatena.ne.jp/chamotarooo/","provider_url":"https://hatena.blog","image_url":null,"published":"2026-10-25 10:08:34","url":"https://chamotaro.hatenablog.com/entry/tech/sql-third-truth-value","author_name":"chamotarooo","blog_title":"chamotarooo\u306e\u30d6\u30ed\u30b0","categories":["\u6280\u8853"],"blog_url":"https://chamotaro.hatenablog.com/","description":"\u306f\u3058\u3081\u306b \u300c\u9054\u4eba\u306b\u5b66\u3076SQL\u5fb9\u5e95\u6307\u5357\u66f8\u300d\u3092\u8aad\u3093\u3067\u3044\u305f\u3089\u3001\u624b\u304c\u6b62\u307e\u3063\u305f\u3002 WHERE age = 20 OR age <> 20 \u3068\u66f8\u3044\u305f\u3002\u5168\u884c\u8fd4\u3063\u3066\u304f\u308b\u3068\u601d\u3063\u3066\u3044\u305f\u3002\u8fd4\u3063\u3066\u3053\u306a\u304b\u3063\u305f\u3002NULL\u3092\u6301\u3064\u884c\u304c\u6d88\u3048\u3066\u3044\u305f\u3002\u7406\u7531\u304c\u308f\u304b\u3089\u306a\u304b\u3063\u305f\u3002 SQL\u306ftrue/false\u306e2\u5024\u8ad6\u7406\u3067\u52d5\u3044\u3066\u3044\u308b\u3068\u601d\u3044\u8fbc\u3093\u3067\u3044\u305f\u3002\u9055\u3063\u305f\u3002SQL\u306funknown\u3092\u52a0\u3048\u305f3\u5024\u8ad6\u7406\u3092\u63a1\u7528\u3057\u3066\u3044\u308b\u3002 NULL\u306e\u5b58\u5728\u304c\u3053\u306e\u7b2c\u4e09\u306e\u771f\u7406\u5024\u3092\u751f\u307f\u51fa\u3057\u3001\u30af\u30a8\u30ea\u306e\u52d5\u4f5c\u3092\u76f4\u611f\u304b\u3089\u9060\u3056\u3051\u308b\u3002 \u3042\u306a\u305f\u306fNULL\u3092\u300c\u7a7a\u306e\u5024\u300d\u3060\u3068\u601d\u3063\u3066\u3044\u306a\u3044\u304b\uff1f SQL\u306b\u306f\u7b2c\u4e09\u306e\u771f\u7406\u5024\u304c\u3042\u308b SQL\u306e\u771f\u7406\u5024\u306f3\u3064\u3060\u3002true\u3001false\u3001\u305d\u3057\u3066 unknown\u3002 \u2026","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fchamotaro.hatenablog.com%2Fentry%2Ftech%2Fsql-third-truth-value\" title=\"SQL\u306e\u7b2c\u4e09\u306e\u771f\u7406\u5024\u3092\u76f4\u8996\u3057\u308d\u3002 - chamotarooo\u306e\u30d6\u30ed\u30b0\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","width":"100%","height":"190","provider_name":"Hatena Blog","title":"SQL\u306e\u7b2c\u4e09\u306e\u771f\u7406\u5024\u3092\u76f4\u8996\u3057\u308d\u3002"}