Mysql 如何在联接查询中基于一列返回最大行数？_Mysql_Sql_Join_Count_Greatest N Per Group

Mysql 如何在联接查询中基于一列返回最大行数？

mysql sql join

Mysql 如何在联接查询中基于一列返回最大行数？,mysql,sql,join,count,greatest-n-per-group,Mysql,Sql,Join,Count,Greatest N Per Group,我有一个查询，它返回一个结果集，其中包含几个表中的一些ID。如果一个数据库获取两行或多行具有相同的QuestionID，那么我只需要具有MAX（QuestionSessionID）的一行。我怎样才能做到这一点我尝试了一系列不同的子查询变体，但没有成功。如何做到这一点查询： SELECT AQS.QuestionSessionID, AQS.QuestionID, AQS.AnswerTextMarkerID, AQS.Correct, QG.ID AS QuestionGroupID FRO

我有一个查询，它返回一个结果集，其中包含几个表中的一些ID。如果一个数据库获取两行或多行具有相同的QuestionID，那么我只需要具有MAX（QuestionSessionID）的一行。我怎样才能做到这一点

我尝试了一系列不同的子查询变体，但没有成功。如何做到这一点

查询：

SELECT AQS.QuestionSessionID, AQS.QuestionID, AQS.AnswerTextMarkerID, AQS.Correct, QG.ID AS QuestionGroupID
FROM AnswerQuestionSession AQS
JOIN QuestionSession QS ON QS.UserID = 3 
JOIN Question Q ON AQS.QuestionID = Q.ID
JOIN QuestionGroup QG ON Q.QuestionGroupID = QG.ID
WHERE AQS.AnswerTextMarkerID IN (109,110,113,114,118,121,141,146,148,152,156,157,158,172,182,183,193,194,196,197,198,211,222,227,241,242,243,257,263,271,282,283,356,396,643,644,938,939,943,944,955,956,957,958,959,970,971,972,973,978,979,1110,1111,1112,1113,1114,1115,1116,1117,1118,1120,1121,1163,1164,1165,1166,1205,1240)
AND AQS.QuestionSessionID = QS.ID
ORDER BY AQS.QuestionID, AQS.QuestionSessionID DESC;

当前结果集：

QuestionSessionID QuestionID AnswerTextMarkerID Correct QuestionGroupID
294441            112        121                1       25
22942             112        121                0       25
22942             126        141                1       39
131489            216        257                1       102
22942             222        263                1       106
22942             227        271                1       110
294435            760        955                1       5
294435            760        956                1       5

QuestionSessionID QuestionID AnswerTextMarkerID Correct QuestionGroupID
294441            112        121                1       25
22942             126        141                1       39
131489            216        257                1       102
22942             222        263                1       106
22942             227        271                1       110
294435            760        955                1       5
294435            760        956                1       5

SELECT AQS.QuestionSessionID, AQS.QuestionID, AQS.AnswerTextMarkerID, AQS.Correct, QG.ID AS QuestionGroupID
FROM AnswerQuestionSession AQS
JOIN QuestionSession QS ON  AQS.QuestionSessionID = QS.ID 
JOIN Question Q ON AQS.QuestionID = Q.ID
JOIN QuestionGroup QG ON Q.QuestionGroupID = QG.ID
JOIN (SELECT QuestionID, MAX(QuestionSessionID) as MaxId
      FROM AnswerQuestionSession AQS2
      JOIN QuestionSession QS2 ON AQS2.QuestionSessionID = QS2.ID
      WHERE QS2.UserID = 3
      GROUP BY QuestionID) as mq ON mq.QuestionID = AQS.QuestionID
WHERE AQS.AnswerTextMarkerID IN (109,110,113,114,118,121,141,146,148,152,156,157,158,172,182,183,193,194,196,197,198,211,222,227,241,242,243,257,263,271,282,283,356,396,643,644,938,939,943,944,955,956,957,958,959,970,971,972,973,978,979,1110,1111,1112,1113,1114,1115,1116,1117,1118,1120,1121,1163,1164,1165,1166,1205,1240)
AND QS.UserID = 3 
AND AQS.QuestionSessionID = MaxId;

因此，在上面的示例中，我只需要问号为112的行中的一行（带有MAX（问号sessionid）294441的行），如下所示：

所需结果集：

QuestionSessionID QuestionID AnswerTextMarkerID Correct QuestionGroupID
294441            112        121                1       25
22942             112        121                0       25
22942             126        141                1       39
131489            216        257                1       102
22942             222        263                1       106
22942             227        271                1       110
294435            760        955                1       5
294435            760        956                1       5

QuestionSessionID QuestionID AnswerTextMarkerID Correct QuestionGroupID
294441            112        121                1       25
22942             126        141                1       39
131489            216        257                1       102
22942             222        263                1       106
22942             227        271                1       110
294435            760        955                1       5
294435            760        956                1       5

SELECT AQS.QuestionSessionID, AQS.QuestionID, AQS.AnswerTextMarkerID, AQS.Correct, QG.ID AS QuestionGroupID
FROM AnswerQuestionSession AQS
JOIN QuestionSession QS ON  AQS.QuestionSessionID = QS.ID 
JOIN Question Q ON AQS.QuestionID = Q.ID
JOIN QuestionGroup QG ON Q.QuestionGroupID = QG.ID
JOIN (SELECT QuestionID, MAX(QuestionSessionID) as MaxId
      FROM AnswerQuestionSession AQS2
      JOIN QuestionSession QS2 ON AQS2.QuestionSessionID = QS2.ID
      WHERE QS2.UserID = 3
      GROUP BY QuestionID) as mq ON mq.QuestionID = AQS.QuestionID
WHERE AQS.AnswerTextMarkerID IN (109,110,113,114,118,121,141,146,148,152,156,157,158,172,182,183,193,194,196,197,198,211,222,227,241,242,243,257,263,271,282,283,356,396,643,644,938,939,943,944,955,956,957,958,959,970,971,972,973,978,979,1110,1111,1112,1113,1114,1115,1116,1117,1118,1120,1121,1163,1164,1165,1166,1205,1240)
AND QS.UserID = 3 
AND AQS.QuestionSessionID = MaxId;

更新： 尝试按照评论员的建议添加另一个加入，但没有正确执行。它似乎只适用于具有多个相同问题ID的行：

SELECT AQS.QuestionSessionID, AQS.QuestionID, AQS.AnswerTextMarkerID, AQS.Correct, QG.ID AS QuestionGroupID, MaxId
FROM AnswerQuestionSession AQS
JOIN QuestionSession QS ON QS.UserID = 3 
JOIN Question Q ON AQS.QuestionID = Q.ID
JOIN QuestionGroup QG ON Q.QuestionGroupID = QG.ID
JOIN (SELECT QuestionID, MAX(QuestionSessionID) as MaxId
      FROM AnswerQuestionSession
      GROUP BY QuestionID) as mq ON mq.QuestionID = AQS.QuestionID
WHERE AQS.AnswerTextMarkerID IN (109,110,113,114,118,121,141,146,148,152,156,157,158,172,182,183,193,194,196,197,198,211,222,227,241,242,243,257,263,271,282,283,356,396,643,644,938,939,943,944,955,956,957,958,959,970,971,972,973,978,979,1110,1111,1112,1113,1114,1115,1116,1117,1118,1120,1121,1163,1164,1165,1166,1205,1240)
AND AQS.QuestionSessionID = QS.ID
/*AND AQS.QuestionSessionID = MaxId*/
ORDER BY AQS.QuestionID, AQS.QuestionSessionID DESC;

更新2:

QuestionSessionID QuestionID AnswerTextMarkerID Correct QuestionGroupID
294441            112        121                1       25
22942             112        121                0       25
22942             126        141                1       39
131489            216        257                1       102
22942             222        263                1       106
22942             227        271                1       110
294435            760        955                1       5
294435            760        956                1       5

QuestionSessionID QuestionID AnswerTextMarkerID Correct QuestionGroupID
294441            112        121                1       25
22942             126        141                1       39
131489            216        257                1       102
22942             222        263                1       106
22942             227        271                1       110
294435            760        955                1       5
294435            760        956                1       5

SELECT AQS.QuestionSessionID, AQS.QuestionID, AQS.AnswerTextMarkerID, AQS.Correct, QG.ID AS QuestionGroupID
FROM AnswerQuestionSession AQS
JOIN QuestionSession QS ON  AQS.QuestionSessionID = QS.ID 
JOIN Question Q ON AQS.QuestionID = Q.ID
JOIN QuestionGroup QG ON Q.QuestionGroupID = QG.ID
JOIN (SELECT QuestionID, MAX(QuestionSessionID) as MaxId
      FROM AnswerQuestionSession AQS2
      JOIN QuestionSession QS2 ON AQS2.QuestionSessionID = QS2.ID
      WHERE QS2.UserID = 3
      GROUP BY QuestionID) as mq ON mq.QuestionID = AQS.QuestionID
WHERE AQS.AnswerTextMarkerID IN (109,110,113,114,118,121,141,146,148,152,156,157,158,172,182,183,193,194,196,197,198,211,222,227,241,242,243,257,263,271,282,283,356,396,643,644,938,939,943,944,955,956,957,958,959,970,971,972,973,978,979,1110,1111,1112,1113,1114,1115,1116,1117,1118,1120,1121,1163,1164,1165,1166,1205,1240)
AND QS.UserID = 3 
AND AQS.QuestionSessionID = MaxId;

根据一位评论员的帮助，我对它进行了一个小小的修改，使它如期工作：

工作查询：

QuestionSessionID QuestionID AnswerTextMarkerID Correct QuestionGroupID
294441            112        121                1       25
22942             112        121                0       25
22942             126        141                1       39
131489            216        257                1       102
22942             222        263                1       106
22942             227        271                1       110
294435            760        955                1       5
294435            760        956                1       5

QuestionSessionID QuestionID AnswerTextMarkerID Correct QuestionGroupID
294441            112        121                1       25
22942             126        141                1       39
131489            216        257                1       102
22942             222        263                1       106
22942             227        271                1       110
294435            760        955                1       5
294435            760        956                1       5

SELECT AQS.QuestionSessionID, AQS.QuestionID, AQS.AnswerTextMarkerID, AQS.Correct, QG.ID AS QuestionGroupID
FROM AnswerQuestionSession AQS
JOIN QuestionSession QS ON  AQS.QuestionSessionID = QS.ID 
JOIN Question Q ON AQS.QuestionID = Q.ID
JOIN QuestionGroup QG ON Q.QuestionGroupID = QG.ID
JOIN (SELECT QuestionID, MAX(QuestionSessionID) as MaxId
      FROM AnswerQuestionSession AQS2
      JOIN QuestionSession QS2 ON AQS2.QuestionSessionID = QS2.ID
      WHERE QS2.UserID = 3
      GROUP BY QuestionID) as mq ON mq.QuestionID = AQS.QuestionID
WHERE AQS.AnswerTextMarkerID IN (109,110,113,114,118,121,141,146,148,152,156,157,158,172,182,183,193,194,196,197,198,211,222,227,241,242,243,257,263,271,282,283,356,396,643,644,938,939,943,944,955,956,957,958,959,970,971,972,973,978,979,1110,1111,1112,1113,1114,1115,1116,1117,1118,1120,1121,1163,1164,1165,1166,1205,1240)
AND QS.UserID = 3 
AND AQS.QuestionSessionID = MaxId;

针对

AnswerQuestionSession

表上的子查询添加联接

JOIN (SELECT QuestionID, MAX(QuestionSessionID as MaxId)
      FROM AnswerQuestionSession
      GROUP BY QuestionID) as mq ON mq. QuestionID = Aqs. QuestionID

然后在

WHERE

子句中使用它

AND Aqs.QuestionSessionID = MaxId

这是基于更新的问题，我更改了QuestionSession上的连接，并确保在WHERE子句中使用了MaxId

SELECT AQS.QuestionSessionID, AQS.QuestionID, AQS.AnswerTextMarkerID, AQS.Correct, QG.ID AS QuestionGroupID
FROM AnswerQuestionSession AQS
JOIN QuestionSession QS ON  AQS.QuestionSessionID = QS.ID
JOIN Question Q ON AQS.QuestionID = Q.ID
JOIN QuestionGroup QG ON Q.QuestionGroupID = QG.ID
JOIN (SELECT QuestionID, MAX(QuestionSessionID) as MaxId
      FROM AnswerQuestionSession
      GROUP BY QuestionID) as mq ON mq.QuestionID = AQS.QuestionID
WHERE AQS.AnswerTextMarkerID IN (109,110,113,114,118,121,141,146,148,152,156,157,158,172,182,183,193,194,196,197,198,211,222,227,241,242,243,257,263,271,282,283,356,396,643,644,938,939,943,944,955,956,957,958,959,970,971,972,973,978,979,1110,1111,1112,1113,1114,1115,1116,1117,1118,1120,1121,1163,1164,1165,1166,1205,1240)
AND QS.UserID = 3 
AND AQS.QuestionSessionID = MaxId
ORDER BY AQS.QuestionID, AQS.QuestionSessionID DESC;

@user9223839感谢您的评论。我尝试过，但没有100%奏效，我用你的建议和新的结果集更新了问题。有什么想法吗？@user9223839根据这条评论更新了问题的工作版本（稍作修改，添加了另一个join以获取maxId）。非常感谢。