具有条件的Sum列和行中的显示

Question

我想对具有多个条件的列进行求和，并在行中显示所有结果

我有一张桌子

Status        Amount
pending         100
Success         50
pending         20
failure         80
success         20

现在我想找到待定，成功和失败的总数

Pending        Success            failure
120             70                 80

类似

select sum(pending), sum(success), sum(failure) from mytable

Answer 1

尝试此查询：

SELECT
   SUM(CASE WHEN Status = 'pending' THEN Amount ELSE 0 END) AS Pending
  ,SUM(CASE WHEN Status = 'Success' THEN Amount ELSE 0 END) AS Success
  ,SUM(CASE WHEN Status = 'Failure' THEN Amount ELSE 0 END) AS Failure
FROM MyTable

您也可以使用此动态查询：

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'SUM(CASE WHEN `Status` = ''',
      `Status`,
      ''' THEN Amount ELSE 0 END) AS `',
      `Status`, '`'
    )
  ) INTO @sql
FROM MyTable;

SET @sql = CONCAT('SELECT ', @sql,'
                     FROM MyTable
                  ');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

请参阅this SQLFiddle