緩慢的SQL查詢

Question

我的網頁有問題。

它的運行速度非常慢，所以我在互聯網上讀到它可能是SQL的一個糟糕用法。所以我評論了更復雜的SQL行，並且它再次順利運行。

我的問題是：'有沒有辦法讓這個SQL請求「更輕」？

@companies = Company.where('tbl_companys.state = "enabled"') 

    @companies = @companies.includes(:benefit).where("tbl_benefits.end_date >= {Date.today}") 

    @companies = @companies.includes(:benefit).where(tbl_benefits: { state: 'enabled' }) 

    has_benef_gastro = false 

    has_benef_hote = false 

    has_benef_ent = false 

    until has_benef_gastro == true 

     @esta_gastro = (@companies.where('id_category = "2-gastronomia"').shuffle)[0] 

     @benefit_gastro = Benefit.where('id_company = ? AND end_date >= ? AND state = "enabled"', @esta_gastro.id_company, Date.today).first 

     if @benefit_gastro.nil? == false 

      has_benef_gastro = true 

     end 

    end 

    until has_benef_hote == true 

     @esta_hotelero = (@companies.where('id_category = "1-hoteleria"').shuffle)[0] 

     @benefit_hote = Benefit.where('id_company = ? AND end_date >= ? AND state = "enabled"', @esta_hotelero.id_company, Date.today).first 

     if @benefit_hote.nil? == false 

      has_benef_gastro = true 

     end 

    end 

    until has_benef_ent == true 

     @esta_ent = (@companies.where('id_category = "3-entretenimiento"').shuffle)[0] 

     @benefit_ent = Benefit.where('id_company = ? AND end_date >= ? AND state = "enabled"', @esta_ent.id_company, Date.today).first 

     if @benefit_ent.nil? == false 

      has_benef_gastro = true 

     end 

    end 

感謝您的幫助！

Answer 1

最後我做一個簡單的SQL請求，所以我並沒有與一些軌道的問題作鬥爭。

無論如何，謝謝！

Answer 2

您每次都在洗牌@esta_gastro，@esta_hotelero,@esta_ent和@benefit_變量，這沒有任何意義。每做一次循環就需要多次新的數據庫查詢。

如果你想找到一個隨機選擇，只需在循環外創建你的集合，一次（在循環之外）洗牌，然後遍歷這些集合，直到你滿足你的標準。

例如：

@esta_gastro = @companies.where('id_category = "2-gastronomia"').shuffle 
@benefits = Benefit.where('end_date >= ? AND state = "enabled"', Date.today) 
@benefit_gastro = nil 
i = 0 
until !@benefit_gastro.blank? 
    @benefit_gastro = @benefits.where('id_company = ?', @esta_gastro[i].id_company).first 
    i += 1 
end 

編輯

如果整個目標是讓@benefit_gastro定義，那麼我甚至不認爲你需要一個循環。您可以定義@esta_gastro集合，然後使用它找到所有對應的優點。由於@esta_gastro被打亂，你@benefit_gastro將是隨機的：

@esta_gastro = @companies.where('id_category = "2-gastronomia"').shuffle 
@benefit_gastro = Benefit.where('end_date >= ? AND state = "enabled"', Date.today).where('id_company = ?', @esta_gastro.map(&:id)).limit(1)