Restoration/remove_null_sqldata.md

Created October 26, 2016 08:27

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mysql GROUP_CONCATで空データを削除

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#mysql GROUP_CONCATで空データを削除

##Before

ID GROUP_CONCAT(VAL) 
1 ,64,66,,203,214,204

##After ID GROUP_CONCAT(VAL) 1 64,66,203,214,204

###置き換え

select id,replace(group_concat(val),',,',',') from test group by id

###ifで判定

select id,group_concat(if(val ='',null, val)) from test group by id

###Nullifを使用する

select id,group_concat(Nullif(val,'')) from test group by id

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