几个子查询的 UNION ALL 需要很长时间

Question

我正在尝试计算下表中的几个项目：

food
apple cider
cake manzana (manzana in spanish == apple)
carrot cake
banana pudding

我希望得到下表：

food	count
apple	2
carrot	1
banana	1

我尝试了以下查询apples：

SELECT 'apple' as placeholder, COUNT(*)
FROM table WHERE (food LIKE '%apple%' OR food LIKE '%manzana%') and date > '10/10/2021'

问题是当我尝试扩展它以将所有食物放在一起时，需要很长时间：

SELECT 'apple' as placeholder, COUNT(*) FROM table WHERE (food LIKE '%apple%' OR food LIKE '%manzana%') and date > '10/10/2021' and ...
UNION ALL
SELECT 'carrot' as placeholder, COUNT(*) FROM table WHERE food LIKE '%carrot%'  and date > '10/10/2021' and ...
UNION ALL
SELECT 'banana' as placeholder, COUNT(*) FROM table WHERE food LIKE '%banana%' and date > '10/10/2021' and ...

还有其他方式来构造这个查询吗？

Answer 1

将您要查找的食物加载到临时表中，然后加入 LIKE：

CREATE TABLE #findfood (food_to_find nvarchar(50));

INSERT INTO #findfood (food_to_find)
VALUES ('apple'),('carrot'),('banana');

CREATE TABLE #food (food_name nvarchar(100));

INSERT INTO #food (food_name)
VALUES ('apple cider'),('cake apple'),('carrot cake'),('banana pudding');

SELECT food_to_find, COUNT(*) AS count_food_name
FROM #findfood
    INNER JOIN #food ON #food.food_name LIKE '%' + #findfood.food_to_find + '%'
GROUP BY food_to_find;

Answer 2

你为什么不这样做：

SELECT CASE WHEN food LIKE '%apple%' THEN 'apple'
            WHEN food LIKE '%carrot%' THEN 'carrot'
            WHEN food LIKE '%banana%' THEN 'banana' END AS placeholder, COUNT(*) 
FROM   Atable 
WHERE  dates > '2021-01-01' ---
GROUP  BY CASE WHEN food LIKE '%apple%' THEN 'apple'
            WHEN food LIKE '%carrot%' THEN 'carrot'
            WHEN food LIKE '%banana%' THEN 'banana' END 

--> 例子：

CREATE TABLE Atable (food VARCHAR(32), dates date);

INSERT INTO Atable VALUES
('qsqszcbananasqwdcqdesc', '2022-01-01'), 
('qsdvdszcbananasqwdcqdeqfeqsdc', '2022-01-01'), 
('qsqszccarrotsqwdcqdesc', '2022-01-01');

--> 结果：

placeholder (Aucun nom de colonne)
banana      2
carrot      1