关于mysql的not null字段有关问题
关于mysql的not null字段问题
今天遇到了一个很蛋疼的问题，关于mysql数据库的，一个设置了not null的整型字段，默认值自定义为 2，当我用insert语句向该字段插入null值的时候，为什么显示的是系统默认自动生成的整型默认值 0，而不是我自定义的默认值 2，非常纠结，如果我不对该字段做任何操作，就会自动填充自定义的默认值，为什么会这样，求高人指点，谢谢。。。。
------解决方案--------------------
null值 也是值， 即不会用默认值。如果你留空，则就会用默认值。
这个很好理解 啊
------解决方案--------------------
null 表示什么都没有
既然对数值类型字段设置了not null
那么什么都没有在数学中不就是 0 吗？
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你若是自定议默认值了，别设为not NULL,插入的时候直接不带这字段，就是默认值
不能为空意思就得须插入值哪怕是空值，插入值了默认值就没啥用了
------解决方案--------------------
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