Oracle PL/SQL/Data Type/NULL

2 meaningless values can"t be compared against one another

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SQL> select 12 from dual where null = null; no rows selected SQL> SQL>

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This in the only way to do it properly to get the desired results

   <source lang="sql">

SQL> select 12 from dual where null is null;

       12

---

       12

1 row selected. SQL> SQL>

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using the nvl function

   <source lang="sql">

SQL> select 12 from dual where nvl(null,"X") = nvl(null,"X");

       12

---

       12

1 row selected. SQL> SQL> SQL>

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