如果有的话，比a和b都取出来再做判断来说效率如何？
This topic created in 4222 days ago, the information mentioned may be changed or developed.
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1
abelyao Nov 20, 2014
不是应该用字段默认值吗
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4
abelyao Nov 20, 2014
SELECT IFNULL(A, B) 试试看…
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5
yanleijava Nov 20, 2014
case when 啊
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6
zts1993 Nov 20, 2014
case when 大法好
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7
fengchang Nov 20, 2014
case when a='' then b else a end
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8
ozking Nov 20, 2014
COALESCE
http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html#function_coalesce 效率肯定比你自己取出来再比较高 |
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9
hisway Nov 20, 2014
COALESCE(A,B) 今天刚用到～
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10
incompatible Nov 20, 2014
case when写出来太冗长了
ifnull和coalesce就够用了 |
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