mysql - 如何获取特定字段的值总和

Question

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SELECT trtm, 
COUNT(CASE WHEN trtm= 'TM' THEN 1 ELSE NULL END) AS Transmission,
COUNT(CASE WHEN trtm= 'TR' THEN 1 ELSE NULL END) AS Transfer,
COUNT(CASE WHEN trtm= 'DL' THEN 1 ELSE NULL END) AS Deletion
(SELECT 
  (SUM( tshares ) AS total WHERE trtm =  'TM'),
  (SUM( tshares ) AS total1 WHERE trtm =  'TR'))
FROM transfer_file
where t_date between '10/1/1992' and '10/2/1992'
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如何获取特定字段的值的总和，我正在获取值的计数但未获取值的总和，该怎么办？如果有人知道请帮助我

Answer 1

您也应该在 SUM 中使用条件聚合:

SELECT trtm, 
COUNT(CASE WHEN trtm= 'TM' THEN 1 ELSE NULL END) AS Transmission,
COUNT(CASE WHEN trtm= 'TR' THEN 1 ELSE NULL END) AS Transfer,
COUNT(CASE WHEN trtm= 'DL' THEN 1 ELSE NULL END) AS Deletion
SUM(CASE WHEN trtm = 'TM' THEN tshares END) AS Total_Transmission,
SUM(CASE WHEN trtm = 'TR' THEN tshares END) AS Total_Transfer
FROM transfer_file
WHERE t_date between '10/1/1992' and '10/2/1992'