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  1. MariaDB Server
  2. MDEV-8792

Check if it's Ok for Item_func_nullif to have two args[x] refer to the same Item

        Details

        • Type: Task
        • Status: Open
        • Priority: Major
        • Resolution: Unresolved
        • Fix Version/s: 10.1
        • Component/s: OTHER
        • Labels:
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          Description

          Item_func_nullif does this trick:

            // Put "a" to args[0] for comparison and to args[2] for the returned value.
  Item_func_nullif(THD *thd, Item *a, Item *b):
    Item_func_hybrid_field_type(thd, a, b, a)  
  {}

          to emulate CASE WHEN a=b THEN NULL ELSE a END

          It seems to work fine, but needs theoretical proves that it's OK to do this way.

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                  • Assignee:
                    bar Alexander Barkov
                    Reporter:
                    bar Alexander Barkov
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                    • Created:
                      Updated: