NULLIF
Sintassi
NULLIF(espr1, espr2)
Spiegazione
Restituisce NULL se è vero che espr1 = espr2, altrimenti restituisce espr1. Questa espressione è equivalente a CASE WHEN espr1 = espr2 THEN NULL ELSE espr1 END.
Esempi
MariaDB [(none)]> SELECT NULLIF(1,1); +-------------+ | NULLIF(1,1) | +-------------+ | NULL | +-------------+ 1 row in set (0.00 sec) MariaDB [(none)]> SELECT NULLIF(1,2); +-------------+ | NULLIF(1,2) | +-------------+ | 1 | +-------------+ 1 row in set (0.00 sec) MariaDB [(none)]>
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