雄辯質疑2個表

Question

即時得到以下錯誤：

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'value' in 'where clause' (SQL: select sum(gross) as value, first_name from clients left join transactions on clients . id = transactions . client_id where value > 0 group by first_name)

從這個功能呢？

$data = DB::table('clients')->leftjoin('transactions','clients.id','=','transactions.client_id') 
     ->select(DB::raw('sum(gross) as value, first_name')) 
     ->where('value','>',0) 
     ->groupBy('first_name') 
     ->get(); 

return $data; 

Answer 1

SQL is evaluated backwards, from right to left. So the where clause is parsed and evaluate prior to the select clause. Because of this the aliasing of sum(gross) to value has not yet occurred.

Aliases can be used in GROUP BY, ORDER BY, or HAVING clauses.

因此，而不是在請在下面一樣使用sum(gross)使用value。

$data = DB::table('clients')->leftjoin('transactions','clients.id','=','transactions.client_id') 
     ->select(DB::raw('sum(gross) as value, first_name')) 
     ->where('sum(gross)','>',0) 
     ->groupBy('first_name') 
     ->get(); 

return $data;