如何在mysql中实现同一表中三个字段的求和

Question

我有一个表，其中包含字段，我想要将来自三个不同字段的数据求和，如下所示。我按如下方式编写了代码，但有错误。所以请帮我编写正确的代码：

    <?php include "config.php"; ?> 
    <?php $results = mysql_query
("SELECT sum(hit),as total from ( 
select hit from sound union 
select hit from soundK union 
select hit from soundD ") ; 
while ( $row = mysql_fetch_array($results) ) 
{ ?> 
<?php echo $row[total];?> <?php }?> 

所以请尽快帮助我们

提前感谢

Answer 1

您有一个额外的,，缺少结尾的)和派生的表别名：

<?php include "config.php"; ?> 
<?php $results = mysql_query(
    "SELECT sum(hit) as total 
    FROM ( 
        SELECT sum(hit) hit from sound 
        UNION ALL SELECT sum(hit) hit from soundK 
        UNION ALL SELECT sum(hit) hit from soundD 
    ) rs") ; 
while ( $row = mysql_fetch_array($results) ) { ?> 
    <?php echo $row['total'];?>
<?php }?> 

如果您想要3个单独的列：

<?php include "config.php"; ?> 
<?php $results = mysql_query(
    "SELECT soundHits, soundKHits, soundDHits
    FROM ( 
        SELECT sum(hit) soundHits from sound
    ) a, (
        SELECT sum(hit) soundKHits from soundK
    ) b, ( 
        SELECT sum(hit) soundDHits from soundD 
    ) c") ; 
while ( $row = mysql_fetch_array($results) ) { ?> 
    soundHits: <?php echo $row['soundHits'] ;?>
    soundKHits: <?php echo $row['soundKHits'] ;?>
    soundDHits: <?php echo $row['soundDHits'] ;?>
<?php }?> 

Answer 2

或者..。

select (
    (select sum(hit) from sound) +
    (select sum(hit) from soundK) +
    (select sum(hit) from soundD))