如何使用COUNT，SUM，CASE和BETWEEN將此SQL查詢轉換為Perl DBIx :: Class？

Question

如何將該SQL查詢轉換為Perl DBIx :: Class代碼？

SELECT COUNT(*) AS num_grads,
       SUM(CASE WHEN employment_status = 1 THEN 1 ELSE 0 END) AS num_employed
  FROM students
 WHERE status = 6  -- 6 means they graduated
   AND grad_date BETWEEN Convert(datetime, ?) AND Convert(datetime, ?)

Answer 1

假設您的意思是DBIx :: Class，那么我可能會選擇：

my $rs = My::Schema->resultset('Students') #
    ->search({
        status => 6,
        grad_date => { 'between' => [ $start_dt, $end_dt ] },
    });

my $num_grads    = $rs->count();
my $num_employed = $rs->search({ employment_status => 1 })->count();

當然，日期時間位將取決於您的日期時間格式，是否自動膨脹/縮小日期時間等。