SQL：根据某些条件返回聚合结果

Question

我需要帮助根据某些列的值（例如状态聚合）在 SQL Server 中得出结论。例如，下面是一个包含服务器任务及其状态的表格。

如果我想返回每个服务器的聚合状态，这里是规则：

• 如果所有服务器任务都处于“提交”状态，则聚合服务器状态为“等待”
• 如果所有任务都处于“完成”状态 - 聚合状态为“完成”
• 如果不满足上述情况，则聚合服务器状态为“IN PROGRESS”

示例表：任务

服务器	任务状态	任务
服务器 1	跑步	1-1
服务器 1	完全的	1-2
服务器 1	已提交	1-3
服务器 2	完全的	2-1
服务器 2	完全的	2-2
服务器 3	已提交	3-1
服务器 3	已提交	3-2

示例查询结果：

服务器	完成
服务器 1	进行中
服务器 2	完毕
服务器 3	等待

到目前为止，我尝试使用以下查询但没有成功：

SELECT Server,
    CASE 
       WHEN Task_Status NOT IN ('RUNNING', 'COMPLETED') THEN 'AWAITING' -- Status SUBMITED
       WHEN Task_Status NOT IN ('RUNNING', 'SUBMITED') THEN 'DONE' -- Status COMPLETED
       ELSE 'IN PROGRESS'
    END Completion
FROM Tasks

Answer 1

你可以用这个：

WITH table_name AS
(
    SELECT 'Server 1' AS server, 'RUNNING' AS task_status, '1-1' AS task UNION ALL
    SELECT 'Server 1' AS server, 'COMPLETED' AS task_status, '1-2' AS task UNION ALL
    SELECT 'Server 1' AS server, 'SUBMITTED' AS task_status, '1-3' AS task UNION ALL
    SELECT 'Server 2' AS server, 'COMPLETED' AS task_status, '2-1' AS task UNION ALL
    SELECT 'Server 2' AS server, 'COMPLETED' AS task_status, '2-2' AS task UNION ALL
    SELECT 'Server 3' AS server, 'SUBMITTED' AS task_status, '3-1' AS task UNION ALL
    SELECT 'Server 3' AS server, 'SUBMITTED' AS task_status, '3-2' AS task 
)

SELECT server,
    CASE 
        WHEN COUNT(DISTINCT task_status) = 1 AND MAX(task_status) = 'SUBMITTED' THEN 'AWAITING'
        WHEN COUNT(DISTINCT task_status) = 1 AND MAX(task_status) = 'COMPLETED' THEN 'DONE'
        ELSE 'IN PROGRESS'
    END AS completion
FROM table_name
GROUP BY server
ORDER BY server;

在sqlfiddle 中测试