結合並使用來自兩個不同表的SQL值的算術運算

我有一張表，其中包含來賓對於事件的數據。我可以檢索的人誰出席（membersAttended）與此查詢次數：結合並使用來自兩個不同表的SQL值的算術運算

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;

要檢索的成員總數（totalMembers）我使用：

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

要得到百分比值（totalPercent）的成員誰參加了總成員，我使用PHP做出這兩個查詢，然後像這樣計算：
```
$totalPercent = number_format(($membersAttended/$totalMembers*100),2); 
```

我已經試過了兩個查詢，並以類似的方式下面的百分比計算相結合，沒有運氣：

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;

我也試圖拓展出列：

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;

這給我的錯誤：

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

如何將這些SQL/PHP查詢/計算組合到一個SQL查詢中？

來源

2016-03-08 Ben

交換'tmc_doorapp_guests克，tmc_users爲了M'有適當的JOIN，即：'tmc_users男，tmc_doorapp_guests g' – mitkosoft

@mitkosoft這工作！添加這個作爲答案，我會接受。爲什麼會這樣？ – Ben

它來自SQL嚴格模式，以便在查詢中遵循嚴格的（即適當的）語法。 – mitkosoft

你可以使用子查詢：

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;

來源

2016-03-08 10:17:05 lad2025

結合並使用來自兩個不同表的SQL值的算術運算

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