https://nalar.dev/tags/null/ Recent content in NULL on Nalar Hugo en-us Thu, 03 Sep 2026 00:00:00 +0700 https://nalar.dev/understand-sql-null-with-three-valued-logic/ Thu, 03 Sep 2026 00:00:00 +0700 https://nalar.dev/understand-sql-null-with-three-valued-logic/ <p><code>NULL</code> is one of the easiest SQL concepts to recognize and one of the easiest to reason about incorrectly.</p> <p>The problem starts when <code>NULL</code> is treated as if it were an ordinary value such as <code>0</code>, an empty string, or the word <code>&quot;unknown&quot;</code>. It is none of those. In SQL, <code>NULL</code> represents the absence of a known value, and comparisons involving that absence often produce a third logical result: <strong>UNKNOWN</strong>.</p>