学步园

        Groupby可以进行分类的合计，如果要进一步进行子分类的合计并在一行显示，关键问题是分类的字段如何被子查询使用。我试了一些办法，觉得这样可行，分类时，就把分类字段名字改了，这样就可以在子查询中使用而不会重复了。——说的比较绕，看例子还是比较清楚的。
 


SELECT BJ,
          (SELECT COUNT(*)
         FROM [1]
         WHERE (性别 = '男') AND (班级 = bj)) AS 男生,
          (SELECT COUNT(*)
         FROM [1]
         WHERE (性别 = '女') AND (班级 = bj)) AS 女生,
          (SELECT COUNT(*)
         FROM [1]
         WHERE (班级 = bj)) AS 总计
FROM (SELECT 班级 AS BJ, *
        FROM [1]) DERIVEDTBL
GROUP BY BJ

附，失败的尝试：

SELECT 班级,
          (SELECT COUNT(*)
         FROM [1] b
         WHERE (性别 = '男') AND (b.班级 = 班级)) AS 男生
FROM [1]
GROUP BY 班级

SELECT 班级,
FROM [1]
WHERE (班级 IN
          (SELECT DISTINCT 班级
         FROM [1]))