可以在SELECT语句中使用子查询来计算table_b中属于销售人员的商店数量，然后将其与主查询联合。下面是一个示例：

SELECT mark1.*, 
    (SELECT COUNT(*) FROM table_b WHERE sales_person = mark1.sales_person)             
as sale_shops
FROM mark1
UNION
SELECT mark2.*, 
    (SELECT COUNT(*) FROM table_b WHERE sales_person = mark2.sales_person) 
as sale_shops
FROM mark2

这将返回mark1和mark2表中的所有列，以及一个名为“销售_shops”的新列，该列包含属于table_b中销售人员的商店计数。
或者，您可以将table_b与mark1和mark2连接起来并使用COUNT（）函数

SELECT mark1.*, COUNT(table_b.sales_person) as sale_shops
FROM mark1
LEFT JOIN table_b ON mark1.sales_person = table_b.sales_person
GROUP BY mark1.sales_person
UNION
SELECT mark2.*, COUNT(table_b.sales_person) as sale_shops
FROM mark2
LEFT JOIN table_b ON mark2.sales_person = table_b.sales_person
GROUP BY mark2.sales_person