GROUP BY重复结果

Question

我在这里不能正确使用struct LinkedNode { long data; LinkedNode* next; }; class LinkedList { public: LinkedList(); ~LinkedList(); LinkedNode* head; long Count; long * Data; void add(long data); void update(); //long get(long index); }; LinkedList::LinkedList(){ this->Count = 0; this->head = NULL; } LinkedList::~LinkedList(){ LinkedNode * temp; while(head){ temp= this->head ; head = head->next; delete temp; } if (Data) delete [] Data; Data=NULL; } void LinkedList::add (long data){ LinkedNode * node = new LinkedNode(); node->data = data; node->next = this->head; this->head = node; this->Count++;} void LinkedList::update(){ this->Data= new long[this->Count]; long i = 0; LinkedNode * node =this->head; while(node){ this->Data[i]=node->data; node = node->next; i++; } } ，为什么GROUP BY无法获取预期的结果。

我无法处理表GROUP BY和fee之间的联接。将fee_tm分配给一个时，一个就可以了，但是根据上表的总行（已将ID分组）提取了另一个行。我曾尝试将GROUP BY分配给这两者，但输出都被加倍了。

预期产量

实际结果

但是这里的行相应地重复了group_by总行，然后将输出提取为

数据库结构

fee_tm

fee_tm.id

费用

id  |   ttl |   year
=====================
1   |   Jan |   1
2   |   Feb |   1
3   |   Mar |   1

cls_fee

id  |   ttl     |   year
========================
1   |   Annual  |   1
2   |   Monthly |   1

学生

id  |   cls_id  |   sec_id  |   fee_id |    fee
================================================
1   |   1       |   1       |   1      |    1000
2   |   1       |   1       |   2      |    560

MYSQL

id  |   ttl |   cls |   sec |   year
====================================
1   |   John|   1   |   1   |   1
2   |   Riya|   1   |   1   |   1

$result=$con->prepare(" SELECT fee_tm.ttl AS f_tm, cls_fee.fee AS f_mnt, fee.ttl AS f_ttl FROM student LEFT JOIN fee_tm ON fee_tm.year = student.year JOIN cls_fee ON cls_fee.sec_id = student.sec AND cls_fee.cls_id = student.cls LEFT JOIN fee ON fee.id = cls_fee.fee_id WHERE student.id =:stdt GROUP BY fee_tm.id"; $results=array(); while($row=$result->fetch(PDO::FETCH_ASSOC)){ $results[]=$row; echo" <input type='checkbox' name='f_id' /'>".$row['f_tm']; } echo "<br/> <table>"; foreach($results as $row1){ echo" <tr> <td>".$row1['f_ttl']."</td> <td>".$row1['f_mnt']."</td> </tr>"; } echo "</table>"; 的结果：

print_r($result->fetchAll(PDO::FETCH_ASSOC))