例如,我有一个名为tbl_grade的表,其中包含以下数据
id | studentid | compid | grade
1 | 1009123456 | 1 | 90
2 | 1009123457 | 2 | 95
3 | 1009123458 | 2 | 90
我的模型中有这行代码
public function gradeSum($studentid)
{
$this->db->where('studentid',$studentid);
$query = $this->db->get('tbl_grade');
return $query->result();
}
在我看来:
<?php foreach ($this->UserModel->gradeSum($student->studentid) as $studentgrade):
if($studentgrade->compid==2){
echo $studentgrade->grade; //the code for the addition of the grades should be put here but for the meantime i just echoed the grades
}
endforeach;?>
foreach语句会给我95和90,这是正确的。但我想重复一下它的总和。我放入了echo $sum->grade + $sum->grade;
,但显然它不起作用,那么正确的语法是什么,这样我才能回显这些值的总和?
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