MySQL NULL 保险就是运算符，至关于规范 SQL IS NOT DISTINCT FROM 运算符，执止雷同于 = 运算符的相称比拟。它的标识表记标帜是。当咱们将 NULL 做为2个垄断数时，它的执止体式格局取比拟运算符差别。请思量下列事例来相识 NULL 保险运算符及其取对照运算符的区别 -
mysql> Select 50 <=> 50, NULL <=> NULL, 100 <=> NULL; +-----------+---------------+--------------+ | 50 <=> 50 | NULL <=> NULL | 100 <=> NULL | +-----------+---------------+--------------+ | 1 | 1 | 0 | +-----------+---------------+--------------+ 1 row in set (0.00 sec) mysql> Select 50 = 50, NULL = NULL, 100 = NULL; +---------+-------------+------------+ | 50 = 50 | NULL = NULL | 100 = NULL | +---------+-------------+------------+ | 1 | NULL | NULL | +---------+-------------+------------+ 1 row in set (0.00 sec)
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以上即是甚么是 MySQL NULL 保险便是运算符和它取比力运算符有何差异？的具体形式，更多请存眷萤水红IT仄台此外相闭文章！
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