如何使用sql對壹個有多個鍵值的字段進行計數?如果鍵相同,則將值相加。
public static void main(String【】args){ String String =“【{ \“depid \“:\“5 \“,\“score \“:\“10 \“},{ \“depid \“:\“4 \“},{ \“depid \“:\“4 \“,\“score \“:\“30 \“},{ \“depid \“:\“5 \“,\“score \:\“30 \“}】“;JSON array from object = JSON array . from object(string);地圖& lt字符串,整數& gtmap = new HashMap & lt字符串,整數& gt();for(Object對象:from Object){ JSON Object JSON Object =(JSON Object)對象;String depid =(String)JSON object . get(“depid“);integer score = integer . value of((String)JSON object . get(“score“));if(map . contains key(depid)){ int integer = map . get(depid);map . put(depid,整數+分數);} else { map . put(depid,score);} } Set & lt條目& lt字符串,整數& gt& gtentry set = map . entry set();JSON array JSON array = new JSON array();for(Entry & lt;字符串,整數& gtentry:entry set){ JSON object JSON object = new JSON object();JSON object . put(“depid“,entry . getkey());JSON object . put(“score“,string . value of(entry . getvalue()));JSON array . add(JSON object);} system . out . println(JSON array . tostring());}