加入表

Question

我在下面的代码目前有效，但在COUNT之后添加ORDER BY后，它给了我错误

  

无效的列名'Answers'

SELECT  Test.SOLUTION_NOT_FOUND, 
        Test.SEARCH_TEST, 
        Test.KEYWORD as Search_Words, 
        Test2.Answers_for_exam AS Answers
FROM    Test 
INNER JOIN  Test2 ON Test.TEST_NUMBER = Test2.TEST_NUMBER
WHERE SOLUTION_NOT_FOUND = 1
ORDER BY COUNT(Answers) DESC

我在第一行尝试了COUNT(Test2.Answers_for_exam) AS Answers但也提供了相同的错误消息。 我是否也可以不显示SOLUTION_NOT_FOUND列。我只是在那里添加它才能看到结果，但不需要看到它。

在Answers列下有重复的字符串。我想按大多数字符串排序。例如：汽车，汽车，纸张，岩石，纸张，纸张。我希望纸张首先返回，然后是汽车然后摇滚，因为纸张有3个计数，汽车有2个计数，摇滚只有1个计数（假设只有3个唯一的字符串）。如果我做ORDER BY Answers DESC，他们将按字母顺序排列。

Answer 1

使用COUNT(*) OVER()窗口函数执行所需的计数，然后按顺序排序

SELECT  Test.SOLUTION_NOT_FOUND, 
        Test.SEARCH_TEST, 
        Test.KEYWORD as Search_Words, 
        Test2.Answers_for_exam AS Answers,
        COUNT(*) OVER (PARTITION BY Test2.Answers_for_exam) AS AnswerCount
FROM    Test 
INNER JOIN  Test2 ON Test.TEST_NUMBER = Test2.TEST_NUMBER
WHERE SOLUTION_NOT_FOUND = 1
ORDER BY AnswerCount DESC

Answer 2

您应该在单独的列（此处为cnt）中跟踪答案数量，然后按照下面的顺序进行排序

SELECT 
    SOLUTION_NOT_FOUND,
    SEARCH_TEST,
    Search_Words,
    Answers
FROM
(
SELECT  Test.SOLUTION_NOT_FOUND, 
        Test.SEARCH_TEST, 
        Test.KEYWORD as Search_Words, 
        Test2.Answers_for_exam AS Answers,
        COUNT(Test2.Answers_for_exam) over ( order by (select 1)) as cnt
FROM    Test 
INNER JOIN  Test2 ON Test.TEST_NUMBER = Test2.TEST_NUMBER
WHERE SOLUTION_NOT_FOUND = 1
)T 
ORDER BY cnt DESC

你也可以使用下面的分组

SELECT  Test.SOLUTION_NOT_FOUND, 
        Test.SEARCH_TEST, 
        Test.KEYWORD as Search_Words, 
        Test2.Answers_for_exam AS Answers
FROM    Test 
INNER JOIN  Test2 ON Test.TEST_NUMBER = Test2.TEST_NUMBER
WHERE SOLUTION_NOT_FOUND = 1
GROUP BY 
        Test.SOLUTION_NOT_FOUND, 
        Test.SEARCH_TEST, 
        Test.KEYWORD as Search_Words, 
        Test2.Answers_for_exam
ORDER BY COUNT(Test2.Answers_for_exam) DESC

Answer 3

您可以在order by中使用窗口功能。所以，我想你想要：

SELECT Test.SOLUTION_NOT_FOUND, 
       Test.SEARCH_TEST, 
       Test.KEYWORD as Search_Words, 
       Test2.Answers_for_exam AS Answers
FROM Test INNER JOIN
     Test2
     ON Test.TEST_NUMBER = Test2.TEST_NUMBER
WHERE SOLUTION_NOT_FOUND = 1
ORDER BY COUNT(*) OVER (PARTITION BY Test2.Answers_for_exam) DESC;

这应该是实现目标的最简单方法。