具有多個表的列的所有行的總和值

Question

我用它來得到總數

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

但我需要從具有相同結構的多個表中獲取它，名為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