[TOC] ### LEFT OUTER JOIN 左外連接 * [ ] 需求：查詢所有分類，如果該分類下沒有商品，則不顯示該分類 * [ ] 實現： ~~~ SELECT `goods`.`id`, `goods`.`title`, `goods`.`price`, `goods`.`cate_id`, `cate`.`id`, `cate`, `cate.title` FROM `goods` LEFT OUTER JOIN `category` AS `cate` ON `goods`.`cate_id` = `cate`.`id`; const cate = await this.ctx.model.Category.findAll({ include: [{ model: this.ctx.model.Goods, as: 'goods', attributes:['title', 'price'], // 實現 左外連接 required: true, }], distinct: true }); ~~~