mysql - 求和列与条件并在行中显示

Question

我想对具有多个条件的列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

现在我想找到未决、成功和失败的总数

Pending        Success            failure
120             70                 80

就像是

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

Answer 1

试试这个查询：

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

您还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;

看到这个 SQLFiddle