Question

我尝试创建数据透视表，但没有使用oracle pivot子句。

当我运行此查询时，我得到以下数据：

SELECT first_name  AS driver 
, v.name AS truck
, COUNT(haul_id) AS "Haul Count"
FROM employee e JOIN haul h
  ON e.employee_id = h.employee_id
JOIN vehicle v
  ON v.vehicle_id = h.vehicle_id
GROUP BY first_name, v.name
ORDER BY first_name, COUNT(haul_id) DESC;

╔════════╦═════════════╦════════════╗
║ Driver ║  Truck      ║ Haul Count ║
╠════════╬═════════════╬════════════╣
║  Judy  ║ Big Dog     ║     5      ║
║  Judy  ║ Classy Cat  ║     5      ║
║  Judy  ║ Mad Max     ║     4      ║
║  Matt  ║ Mad Max     ║     8      ║
║  Matt  ║ Classy Cat  ║     8      ║
║  Matt  ║ Big Dog     ║     5      ║
║  Troy  ║ Mad Max     ║     8      ║
║  Troy  ║ Big Dog     ║     4      ║
║  Troy  ║ Classy Cat  ║     3      ║
╚════════╩═════════════╩════════════╝

现在我想生成一个报告，显示相同的数据但是在数据透视布局中：

╔════════╦══════════╦════════════╦════════╗
║ Driver ║  Big Dog ║ Classy Cat ║ Mad Max║
╠════════╬══════════╬════════════╬════════╣
║  Judy  ║    5     ║     5      ║    4   ║
║  Matt  ║    5     ║     8      ║    8   ║
║  Troy  ║    4     ║     3      ║    8   ║  
╚════════╩══════════╩════════════╩════════╝

经过大量的实验和试验，我的代码变得越来越大，并且它返回了绝对总数：

SELECT first_name
, (SELECT COUNT(h.vehicle_id) 
FROM employee e JOIN haul h
 ON e.employee_id = h.employee_id
  JOIN vehicle v
    ON v.vehicle_id = h.vehicle_id
 WHERE v.name = 'Big Dog') AS "Big Dog"
 FROM haul JOIN vehicle
  ON haul.vehicle_id = vehicle.vehicle_id
 WHERE vehicle.name = 'Classy Cat') AS "Classy Cat"
 , (SELECT COUNT(haul.vehicle_id) 
    FROM haul JOIN vehicle
      ON haul.vehicle_id = vehicle.vehicle_id
    WHERE vehicle.name = 'Mad Max') AS "Mad Max"
 FROM employee e JOIN haul h
  ON e.employee_id = h.employee_id
   JOIN vehicle v
    ON v.vehicle_id = h.vehicle_id
 GROUP BY first_name
 ORDER BY first_name ASC;


 ╔════════╦══════════╦════════════╦════════╗
 ║ Driver ║  Big Dog ║ Classy Cat ║ Mad Max║
 ╠════════╬══════════╬════════════╬════════╣
 ║  Judy  ║    14    ║     16     ║    20  ║
 ║  Matt  ║    14    ║     16     ║    20  ║
 ║  Troy  ║    14    ║     16     ║    20  ║  
 ╚════════╩══════════╩════════════╩════════╝

关于如何使其有效并且仅返回每辆卡车的每个驾驶员的数量的任何想法？

由于

Answer 1

您可以使用条件聚合：

SELECT first_name
        , COUNT(CASE 
                   WHEN vehicle.name = 'Classy Cat' THEN h.vehicle_id 
                END) AS 'Classy Cat' 
        , COUNT(CASE 
                   WHEN vehicle.name = 'Big Dog' THEN h.vehicle_id 
                END) AS 'Big Dog' 
        , COUNT(CASE 
                   WHEN vehicle.name = 'Mad Max' THEN h.vehicle_id 
                END) AS 'Mad Max' 
FROM employee e 
JOIN haul h ON e.employee_id = h.employee_id
JOIN vehicle v ON v.vehicle_id = h.vehicle_id
GROUP BY first_name
ORDER BY first_name ASC;

Answer 2

使用数据透视查询并仅对名字进行汇总：

SELECT
    first_name AS driver,
    SUM(CASE WHEN v.name = 'Big Dog'    THEN 1 ELSE 0 END) AS "Big Dog",
    SUM(CASE WHEN v.name = 'Classy Cat' THEN 1 ELSE 0 END) AS "Classy Cat",
    SUM(CASE WHEN v.name = 'Mad Max'    THEN 1 ELSE 0 END) AS "Max"
FROM employee e JOIN haul h
    ON e.employee_id = h.employee_id
JOIN vehicle v
    ON v.vehicle_id = h.vehicle_id
GROUP BY first_name
ORDER BY first_name

SQL在不使用Oracle Pivot子句的情况下创建数据透视表

2 个答案: