A.
CREATE VIEW v1 AS SELECT 所在系, COUNT(*) FROM 学生表 GROUP BY 所在系
B.
CREATE VIEW v1 AS SELECT 所在系, SUM(*) FROM 学生表 GROUP BY 所在系
C.
CREATE VIEW v1(系名,人数) AS SELECT 所在系, SUM(*) FROM 学生表 GROUP BY 所在系
D.
CREATE VIEW v1(系名,人数) AS SELECT 所在系, COUNT(*) FROM 学生表 GROUP BY 所在系