不能通過

select sum(total) from (
(select sum(team1_score) as total from country,match_results where country_name=team1 group by country_name as s1) 
UNION ALL 
(select sum(team2_score) as total from country,match_results where country_name=team2 group by country_name as s2) 
);

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2017-09-25 nikhil kekan

從

select sum(total) from (
    select sum(team1_score) as total 
    from country,match_results 
    where country_name=team1 
    group by country_name 
    UNION ALL 
    select sum(team2_score) 
    from country,match_results 
    where country_name=team2 
    group by country_name 
) T

刪除在選擇第二別名和別名爲組和assigna真名的子查詢，您應該使用顯式的內部連接

select sum(total) from (
    select sum(team1_score) as total 
    from country 
    inner join match_results on country.country_name=team1 and 
    match_results.team1=team1 
    group by country_name 
UNION ALL 
    select sum(team2_score) 
    from country 
    inner join match_results on country.country_name=team2 and 
    match_results.team2=team2 
    group by country_name 
) T

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2017-09-25 18:30:19 scaisEdge

非常感謝scaisEdge，兩種解決方案現在工作得很好。但在第二個建議使用內部連接，你可以解釋爲什麼使用兩個條件 country.country_name = team2和match_results.team2 = team2？ –

是相同的..我hav eopted這個，因爲更容易理解，但你也可以使用國家內部聯接match_results country.country_name = match_results.country_name和country.country_name = team1 ...是一樣的...使用傳遞屬性或不結果不改變 – scaisEdge

@nikhilkekan好，如果我的回答是正確的請標記爲接受...看到這裏如何 http://meta.stackexchange.com/questions/5234/how-does -accepting-的回答工作 – scaisEdge

嘗試移除即別名as s1和as s2

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2017-09-25 18:26:28

試過沒有工作，我還是謝謝你 –

別名應是子查詢外，使用組中的SQL兩個查詢的結合; MySQL可能認爲你試圖（毫無意義地）混淆了分組標準。

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2017-09-25 18:29:50 Uueerdo

嘗試沒有工作，無論如何謝謝 –

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