结合并使用来自两个不同表的SQL值的算术运算

我有一张表，其中包含来宾对于事件的数据。我可以检索的人谁出席（membersAttended）与此查询次数：结合并使用来自两个不同表的SQL值的算术运算

SELECT COUNT(DISTINCT g.`name1`) AS `membersAttended` 
    FROM `tmc_doorapp_guests` g 
    LEFT JOIN `tmc_doorapp_events` e 
    ON e.`id` = g.`event_id` 
    WHERE `name1` REGEXP '^[0-9]+$' 
    AND e.`date` > DATE_SUB(NOW(), INTERVAL 30 DAY) 
    AND g.`checkin` = 1;

要检索的成员总数（totalMembers）我使用：

SELECT COUNT(DISTINCT `id`) AS `totalMembers` 
    FROM `tmc_users`;

要得到百分比值（totalPercent）的成员谁参加了总成员，我使用PHP做出这两个查询，然后像这样计算：
```
$totalPercent = number_format(($membersAttended/$totalMembers*100),2); 
```

我已经试过了两个查询，并以类似的方式下面的百分比计算相结合，没有运气：

SELECT COUNT(DISTINCT g.`name1`) AS `membersAttended`, 
     COUNT(DISTINCT m.`id`) AS `totalMembers`, 
     (`membersAttended` * 100/`totalMembers`) AS `totalPercent` 
     FROM `tmc_doorapp_guests` g, `tmc_users` m 
     LEFT JOIN `tmc_doorapp_events` e 
     ON e.`id` = g.`event_id` 
     WHERE `name1` REGEXP '^[0-9]+$' 
     AND e.`date` > DATE_SUB(NOW(), INTERVAL 30 DAY) 
     AND g.`checkin` = 1;

我也试图拓展出列：

SELECT COUNT(DISTINCT g.`name1`) AS `membersAttended`, 
     COUNT(DISTINCT m.`id`) AS `totalMembers`, 
     (COUNT(DISTINCT g.`name1`) * 100/COUNT(DISTINCT m.`id`)) AS `totalPercent` 
     FROM `tmc_doorapp_guests` g, `tmc_users` m 
     LEFT JOIN `tmc_doorapp_events` e 
     ON e.`id` = g.`event_id` 
     WHERE `name1` REGEXP '^[0-9]+$' 
     AND e.`date` > DATE_SUB(NOW(), INTERVAL 30 DAY) 
     AND g.`checkin` = 1;

这给我的错误：

Error code: 1054. Unknown column 'g.event_id' in 'on clause'

如何将这些SQL/PHP查询/计算组合到一个SQL查询中？

来源

2016-03-08 Ben

交换'tmc_doorapp_guests克，tmc_users为了M'有适当的JOIN，即：'tmc_users男，tmc_doorapp_guests g' – mitkosoft

@mitkosoft这工作！添加这个作为答案，我会接受。为什么会这样？ – Ben

它来自SQL严格模式，以便在查询中遵循严格的（即适当的）语法。 – mitkosoft

你可以使用子查询：

SELECT COUNT(DISTINCT g.`name1`) AS `membersAttended`, 
     (SELECT COUNT(DISTINCT `id`) FROM `tmc_users`) AS `totalMembers`, 
     COUNT(DISTINCT g.`name1`) * 100/(SELECT COUNT(DISTINCT `id`) 
              FROM `tmc_users`) AS `totalPercent` 
FROM `tmc_doorapp_guests` g 
LEFT JOIN `tmc_doorapp_events` e 
ON e.`id` = g.`event_id` 
WHERE `name1` REGEXP '^[0-9]+$' 
AND e.`date` > DATE_SUB(NOW(), INTERVAL 30 DAY) 
AND g.`checkin` = 1;

来源

2016-03-08 10:17:05 lad2025

结合并使用来自两个不同表的SQL值的算术运算

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