Question

我需要根据PERSON_ID连接两个表，并收集每个person_ID的平均成绩的平均值，仅包括数值。这两个表格被称为学生和成绩。我需要将列PERSON_ID，ENROLL_PERIOD和GRADE组合在一起到目前为止我已经尝试了

select students.PERSON_ID, students.ENROLL_PERIOD, AVG(Cast(grades.GRADE as numeric))
from Students
INNER JOIN Grades on Students.PERSON_ID = Grades.PERSON_ID
where ENROLL_PERIOD IS NOT NULL AND ENROLL_PERIOD <> ''
Order by ENROLL_PERIOD ASC
GROUP BY PERSON_ID,ENROLL_PERIOD

我收到错误：

关键字＆＃39; GROUP＆＃39;附近的语法不正确。 [156]（严重程度15）

表格如下：

PERSON ID : ENROLL_PERIOD : GRADE
_________________________________
12401     :  109          :  4 
12401     :  109          :  7
12401     :  109          :  B
43245     :  112          :  12
43245     :  112          :  IB

我不确定，如果我朝着正确的方向前进，那么如果有人能帮助我，我将非常感激。我是MS SQL的新手。

Answer 1

你需要把订单作为最后一个声明，并且您需要排除所有非数值，然后才能在avg函数中使用它们这样的事可能

declare @students table(person_id int, enroll_period int)
declare @grades table(person_id int, grade varchar(2))

insert into @students values (12401, 109), (43245, 112)
insert into @grades values(12401, '4'), (12401, '7'), (12401, 'B'), (43245, '12'), (43245, 'IB')

select s.PERSON_ID, 
       s.ENROLL_PERIOD,
       avg( case when isnumeric(g.grade) = 1 then convert(int, g.grade) else null end) as AvgGrade
from   @students s
  INNER JOIN @grades g on s.PERSON_ID = g.PERSON_ID
where  ENROLL_PERIOD IS NOT NULL AND ENROLL_PERIOD <> ''
GROUP BY s.PERSON_ID, ENROLL_PERIOD
Order by ENROLL_PERIOD ASC

返回以下结果

PERSON_ID   ENROLL_PERIOD   AvgGrade    
---------   -------------   ------- 
12401       109             5   
43245       112             12

修改
在你的实际表格上它可能看起来像这样：

select s.PERSON_ID, s.ENROLL_PERIOD, avg( case when isnumeric(g.grade) = 1 then convert(int, g.grade) else null end) as AvgGrade from students s INNER JOIN grades g on s.PERSON_ID = g.PERSON_ID where ENROLL_PERIOD IS NOT NULL AND ENROLL_PERIOD <> '' GROUP BY s.PERSON_ID, ENROLL_PERIOD Order by ENROLL_PERIOD ASC

Answer 2

print_r($btypes);
        //Array ( [0] => 11x13 Red and Yellow 2 [1] => Party Bounce and Slide 13 x 18 )

        if(in_array("12x15 Purple and Yellow 2" || "11x13 Red and Yellow 1" || "12x15 Yellow and Purple old" || "11x13 Red and Yellow 2" || "12x15 Purple and Yellow 1" ,$btypes) && 
        in_array("Bootcamp Obstacle Course" ||  "Terminator Torment Obstacle Course" || "Lizard Obstacle Course" || "Bugs Obstacle Course" || "Nemo Obstacle Course",$btypes))
        {
            return "Standard Bouncy Castle and an Obstacle Course";
        }

排序依据

分组

Answer 3

您需要在排序之前按语法放置组。

引自https://blog.sqlauthority.com/2007/06/14/sql-server-easy-sequence-of-select-from-join-where-group-by-having-order-by/

sql语法顺序：

    SELECT yourcolumns
    FROM tablenames
    JOIN tablenames
    WHERE condition
    GROUP BY yourcolumns
    HAVING aggregatecolumn condition
    ORDER BY yourcolumns

MS SQL：连接三个表并仅从数值计算平均值

3 个答案: