網上轉的,挺經典的

SQL查詢?pid???pnum???sid??
??1?????10?????1??
??1?????12?????2??
??2?????8??????3??
??3?????11?????1??
??3?????10?????3??
?寫一個查詢語句使其表現為：??
?pid??s1id??s2id??s3id??
?1????10?????12????0??
?2????0??????0?????8??
?3????11?????0?????10??
???
?解決辦法：??
?select?pid,??
????sum(case?when?sid?=1?then?pnum?else?0?end)?as?'s1id',??
????sum(case?when?sid?=2?then?pnum?else?0?end)?as?'s2id',??
????sum(case?when?sid?=3?then?pnum?else?0?end)?as?'s3id'??
?from?xyz（表名）??
?group?by?pid???
?order?by?pid??

?

轉載于:https://www.cnblogs.com/huangjingzhou/articles/1945687.html

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