具有多个表的列的所有行的总和值

Question

我用它来得到总数

$exe = mysql_query('SELECT SUM(field_3) FROM t_a');
$res = mysql_fetch_row($exe);
echo 'Total Count: ' .$res[0] . ' / XX';

但我需要从具有相同结构的多个表中获取它，名为t_a，t_b，一直到t_z

Answer 1

你可以在我的sql中使用Union All

select sum(field_3) total
from
(
    select field_3
    from t_a
    union all
    select field_3
    from t_b
) t
group by field_3