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Saturday, December 29, 2012

[MYSQL][好文] mysql 中判断null

mysql 中判断null

如果a欄位的值是NULL
a IS NULL 搜尋的到
a = '' 搜尋不到


如果a欄位的值=''
a IS NULL 搜尋不到
a = '' 搜尋的到

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