mysql - 来自两个数据库的mysql总和

Question

SELECT  db1.table.listener, 
        db2.table.listener, 
        SEC_TO_TIME( SUM( TIME_TO_SEC( db2.table.time ) ) + ( TIME_TO_SEC( db1.table.time ) ) ), 
        count( db2.table.listener )
FROM    table
   INNER JOIN db2.table 
        ON db1.table.listener = db2.table.listener
WHERE db2.table.ldate = '19.02.2013'
   AND db1.table.ldate = '19.02.2013'
GROUP BY db2.table.listener, db1.table.listener

我在两个不同的数据库中有两个表，它们具有相同的列（侦听器、时间、日期）。我需要总结时间并按听众分组。此查询提供多条记录，我只需要“听众、总时间、收听次数”。我怎样才能用一个查询来做到这一点？

期望的结果；

| listeners (from both table, full join) | count of values (from both table) | sum of time (from both table) |

Answer 1

请参阅以下内容：

SELECT  db1.table.listener, 
        SEC_TO_TIME( SUM( TIME_TO_SEC( db2.table.time ) ) + 
           ( TIME_TO_SEC( db1.table.time ) ) ), 
        count( db1.table.listener )
FROM    table
   INNER JOIN db2.table 
        ON db1.table.listener = db2.table.listener

WHERE db1.table.ldate = '19.02.2013'

GROUP BY db1.table.listener