查詢學生表中 根據班級 分組，查詢班級總人數，男生人數，女生人數

SELECT A.ClassName AS 班級名稱,
COUNT(ALL A.StudentName) AS 總人數,
SUM( CASE
WHEN Sex = '男' THEN
1
ELSE
0
END
) AS 男生人數,
SUM( CASE
WHEN Sex = '女' THEN
1
ELSE
0
END
) AS 女
FROM [dbo].[Student] A
GROUP BY A.ClassName;