存储最大子字符串值

Question

$exmp = DB::table('cr_tblcomplaintregistration')
            ->select(DB::raw('MAX(CAST(SUBSTRING(complaintRegNo,16,length(complaintRegNo))+1 AS int))'))->first();
        dd($exmp);

我明白了：

{#337 ▼
  +"MAX(CAST(SUBSTRING(complaintRegNo,16,length(complaintRegNo))+1 AS int))": 51
}

如何将值51存储在另一个变量中？。

Answer 1

我假设问题是可变名称？如果是这样，您可以添加SQL别名：

->select(
DB::raw('MAX(CAST(SUBSTRING(complaintRegNo,16,length(complaintRegNo))+1 AS int)) AS maximum')
)

如果您希望$exmp成为列值，只需将该属性添加到链的末尾即可：

$exmp = DB::table('cr_tblcomplaintregistration')
->select(DB::raw('MAX(CAST(SUBSTRING(complaintRegNo,16,length(complaintRegNo))+1 AS int)) as maximum'))
->first()
->maximum;

当然，如果事先first()不为空，您可能希望得到。