mysql小技巧-不寫函數實現split截取 1. 不寫函數實現split截取 場景：dayNewStat+meilishuo+ipad+2003 （dayNewStat+meilishuo+iphone+2003）(dayNewStat+meilishuo+android+2003) 只取最後一位 設想：split('+')[-1] (python寫法) 實現：有嚴格的格式要求，取巧方法，無技術含量
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substring(record_tag,locate('+',replace(record_tag,'dayNewStat+meilishuo+',' dayNewStat-meilishuo-')))
2. having + min + if
場景：只要status是ok的，且id最小
id type status 001 aaa ok 002 aaa error 010 aaa ok 003 bbb ok
實現：去重 & 按條件篩選
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select stat_date,record_tag,substring(record_tag,locate('+',replace(record_tag,'dayNewStat+meilishuo+',' dayNewStat-meilishuo-'))) as client_id,attr_value
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from t_stat_daynew_classify_201306
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where record_type='dayNewStat+app+device+clientID' and record_tag like 'dayNewStat+meilishuo+%' and attr_name ='totalDID' and attr_name_hash = 1380872519 and record_type_hash = 2039497004
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group by stat_date,record_tag
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having min(id) and if( (client_id>10000 and record_tag like 'dayNewStat+meilishuo+android%') or (client_id>2000 and client_id<5000 and record_tag like 'dayNewStat+meilishuo+ipad%') or (client_id>5000 and client_id<10000),'ok','del' ) = 'ok' order by stat_date,client_id
