雄辩质疑2个表

Question

即时得到以下错误：

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)

从这个功能呢？

$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，而不是在请在下面一样使用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;