Question

如何让mysql requst选择包含list的所有元素的所有值。我有这样的表：

+--------+------------+
| carID  | serviceID  |
+--------+------------+
|   1    |      12    |
+--------+------------+
|   1    |      13    |
+--------+------------+
|   1    |      15    |
+--------+------------+
|   2    |      12    |
+--------+------------+
|   3    |      13    |
+--------+------------+
|   3    |      15    |
+--------+------------+

我提出的请求如下：

SELECT `carID` FROM `car_services` WHERE `carID` in (1, 2, 3) AND `serviceID` in (12, 13, 15);

但它会返回所有车辆，但我只需要carID = 1车，因为只有这辆车适合这种情况（支持所有服务12,13,15）。

有什么想法吗？

Answer 1

一种简单的方法是group by和having

SELECT `carID` 
FROM `car_services` 
WHERE `carID` in (1, 2, 3) AND `serviceID` in (12, 13, 15)
group by carID
having count(*) = 3
;

Answer 2

使用GROUP BY和HAVING条款：

SELECT `carID` 
FROM `car_services` 
WHERE `carID` in (1, 2, 3) 
GROUP BY `carID`
HAVING SUM(CASE WHEN `serviceID` in (12,13,15) THEN 1 ELSE 0 END)=3

Answer 3

使用复合where子句来单独检查EXISTS非常简单，并且不依赖于serviceid-carid关系的唯一性。我看一下查询计划/执行成本，然后决定它实际上比分组解决方案更好（如果它是唯一的。）

SELECT carID
  FROM car_services a
 WHERE EXISTS (SELECT 1 FROM car_services b WHERE a.carID = b.car_id AND serviceID = 12)
   AND EXISTS (SELECT 1 FROM car_services b WHERE a.carID = b.car_id AND serviceID = 13)
   AND EXISTS (SELECT 1 FROM car_services b WHERE a.carID = b.car_id AND serviceID = 15)

注意：对于许多必需的服务而言，这显然不能很好地扩展。

Answer 4

您可以使用GROUP_CONCAT：

SELECT carID
FROM (
  SELECT carID, 
         GROUP_CONCAT(DISTINCT serviceID ORDER BY serviceID) AS allServices
  FROM car_services
  WHERE serviceID in (12, 13, 15)
  GROUP BY carID ) t
WHERE allServices = "12,13,15";

即使您在serviceID字段中有重复项，这也会有用。

mysql选择与列表

4 个答案: