Question

我有一个查询来计算一所大学的学生（按类型划分）有多少吃食物类别（例如蔬菜，肉类，鱼......）。

我数据库中的每种菜肴都有一个id dish_composition。我写了查询，但计算所有类别使用711秒（12分钟）。这是非常低效的。你能帮我缩短执行时间吗？

这是查询：

<?php    
$query=(SELECT SUM(uomini) as uomini_carne, SUM(donne) as donne_carne FROM ( SELECT SUM(case when person.sex='M' then 1 end) as uomini, SUM(case when person.sex='F' then 1 end) as donne FROM `dish` JOIN dish_bought ON dish.id_dish=dish_bought.id_dish JOIN meal_receipt ON dish_bought.id_receipt=meal_receipt.id_receipt JOIN relation ON meal_receipt.id_stu=relation.id_stu JOIN person ON relation.id_pers=person.id_pers WHERE dish.dish_composition BETWEEN 51 AND 54 GROUP BY dish.dish_composition) carne)
    UNION ALL
    (SELECT SUM(uomini) as uomini_carne, SUM(donne) as donne_carne FROM ( SELECT SUM(case when person.sex='M' then 1 end) as uomini, SUM(case when person.sex='F' then 1 end) as donne FROM `dish` JOIN dish_bought ON dish.id_dish=dish_bought.id_dish JOIN meal_receipt ON dish_bought.id_receipt=meal_receipt.id_receipt JOIN relation ON meal_receipt.id_stu=relation.id_stu JOIN person ON relation.id_pers=person.id_pers WHERE dish.dish_composition BETWEEN 10 AND 34 GROUP BY dish.dish_composition) primo)
    UNION ALL
    (SELECT SUM(uomini) as uomini_carne, SUM(donne) as donne_carne FROM ( SELECT SUM(case when person.sex='M' then 1 end) as uomini, SUM(case when person.sex='F' then 1 end) as donne FROM `dish` JOIN dish_bought ON dish.id_dish=dish_bought.id_dish JOIN meal_receipt ON dish_bought.id_receipt=meal_receipt.id_receipt JOIN relation ON meal_receipt.id_stu=relation.id_stu JOIN person ON relation.id_pers=person.id_pers WHERE dish.dish_composition BETWEEN 60 AND 62 GROUP BY dish.dish_composition) pesce)
    UNION ALL
    (SELECT SUM(uomini) as uomini_carne, SUM(donne) as donne_carne FROM ( SELECT SUM(case when person.sex='M' then 1 end) as uomini, SUM(case when person.sex='F' then 1 end) as donne FROM `dish` JOIN dish_bought ON dish.id_dish=dish_bought.id_dish JOIN meal_receipt ON dish_bought.id_receipt=meal_receipt.id_receipt JOIN relation ON meal_receipt.id_stu=relation.id_stu JOIN person ON relation.id_pers=person.id_pers WHERE dish.dish_composition IN (71,72,81,82,93) GROUP BY dish.dish_composition) verdura)
    UNION ALL
    (SELECT SUM(uomini) as uomini_carne, SUM(donne) as donne_carne FROM ( SELECT SUM(case when person.sex='M' then 1 end) as uomini, SUM(case when person.sex='F' then 1 end) as donne FROM `dish` JOIN dish_bought ON dish.id_dish=dish_bought.id_dish JOIN meal_receipt ON dish_bought.id_receipt=meal_receipt.id_receipt JOIN relation ON meal_receipt.id_stu=relation.id_stu JOIN person ON relation.id_pers=person.id_pers WHERE dish.dish_composition BETWEEN 91 AND 92 GROUP BY dish.dish_composition) uova)
    UNION ALL
    (SELECT SUM(uomini) as uomini_carne, SUM(donne) as donne_carne FROM ( SELECT SUM(case when person.sex='M' then 1 end) as uomini, SUM(case when person.sex='F' then 1 end) as donne FROM `dish` JOIN dish_bought ON dish.id_dish=dish_bought.id_dish JOIN meal_receipt ON dish_bought.id_receipt=meal_receipt.id_receipt JOIN relation ON meal_receipt.id_stu=relation.id_stu JOIN person ON relation.id_pers=person.id_pers WHERE dish.dish_composition IN (101,101,212) GROUP BY dish.dish_composition) formaggi)
    UNION ALL
    (SELECT SUM(uomini) as uomini_carne, SUM(donne) as donne_carne FROM ( SELECT SUM(case when person.sex='M' then 1 end) as uomini, SUM(case when person.sex='F' then 1 end) as donne FROM `dish` JOIN dish_bought ON dish.id_dish=dish_bought.id_dish JOIN meal_receipt ON dish_bought.id_receipt=meal_receipt.id_receipt JOIN relation ON meal_receipt.id_stu=relation.id_stu JOIN person ON relation.id_pers=person.id_pers WHERE dish.dish_composition=83 GROUP BY dish.dish_composition) legumi)
    UNION ALL
    (SELECT SUM(uomini) as uomini_carne, SUM(donne) as donne_carne FROM ( SELECT SUM(case when person.sex='M' then 1 end) as uomini, SUM(case when person.sex='F' then 1 end) as donne FROM `dish` JOIN dish_bought ON dish.id_dish=dish_bought.id_dish JOIN meal_receipt ON dish_bought.id_receipt=meal_receipt.id_receipt JOIN relation ON meal_receipt.id_stu=relation.id_stu JOIN person ON relation.id_pers=person.id_pers WHERE dish.dish_composition=415 GROUP BY dish.dish_composition) frutta)";
?>

Answer 1

应该是类似的......你必须完成案例陈述......

如果你不能使用IIF，那么用Case

替换

1）转换原始数据
2）总结原始数据

SELECT
  SUM(iif(x.gender = 'F',1,0)) AS Female,
  SUM(iif(x.gender = 'M',1,0)) AS Male,
  x.DishName 
FROM 
(SELECT
  person.sex as gender,
  case  
       when dish.dish_composition BETWEEN 51 AND 54 then 'carne'
       when .... then 'dish 2'
       when .... then 'dish 3'
       else 'dish 100'
  end as DishName
FROM dish
JOIN dish_bought
  ON dish.id_dish = dish_bought.id_dish
JOIN meal_receipt
  ON dish_bought.id_receipt = meal_receipt.id_receipt
JOIN relation
  ON meal_receipt.id_stu = relation.id_stu
JOIN person
  ON relation.id_pers = person.id_pers
) x

group by x.gender, x.DishName

优化查询SQL

1 个答案: