There is an excellent SO on MySQL empty strings versus NULL here, MySQL, better to insert NULL or empty string?, however it doesn't take in to account 'uniformity' - i.e. if you want to have just one choice in your tables (i.e. empty string OR NULL), which should it be?
MySQL空字符串上有一个很好的SO而不是这里的NULL，MySQL，最好插入NULL或空字符串？但是它没有考虑到“一致性” - 即如果你想在你的表中只有一个选择（即空字符串OR NULL），它应该是什么？
My question is, can I get MySQL to automatically store empty strings as NULLs?
我的问题是，我可以让MySQL自动将空字符串存储为NULL吗？
After reading the previous SO I am generally inclined to store NULL but the problem is that I have a lot of PHP forms with optional fields, and (when left blank) these return empty strings.
在阅读了之前的SO后，我通常倾向于存储NULL，但问题是我有很多带有可选字段的PHP表单，并且（当留空时）这些返回空字符串。
2 个解决方案
#1
28
You can enclose your strings with NULLIF()
你可以用NULLIF（）括起你的字符串
You use it like this:
你这样使用它：
NULLIF('test','') --> returns 'test'
NULLIF('' ,'') --> returns NULL
#2
1
Alternatively to NULLIF you could set the default to NULL and just not pass empty fields along.
对于NULLIF，您可以将默认值设置为NULL，而不是传递空字段。
#1
28
You can enclose your strings with NULLIF()
你可以用NULLIF（）括起你的字符串
You use it like this:
你这样使用它：
NULLIF('test','') --> returns 'test'
NULLIF('' ,'') --> returns NULL
#2
1
Alternatively to NULLIF you could set the default to NULL and just not pass empty fields along.
对于NULLIF，您可以将默认值设置为NULL，而不是传递空字段。