php - 如何在我的查询 CODEIGNITER 中使用 DISTINCT

Question

$q = $this->db->select('
             books.title,
             reserved_books.id,
             reserved_books.isbn, 
             reserved_books.price,
             reserved_books.item_sold,
             reserved_books.date_sold,
             reserved_books.total_amount
            ')
        ->from('reserved_books')
        ->join('books','reserved_books.isbn= books.isbn')
        ->limit($limit,$offset);

如何在查询中使用 distinct here？reserved_books.isbn 是独一无二的。

Answer 1

尝试以下:

$this->db->distinct();

但 Distinct 并不总是有效。您应该添加 ->group_by("name_of_the_column_which_needs_to_be unique");

$this->db->group_by('column_name');