-- 19、按各科成绩进行排序，并显示排名(实现不完全)

SELECT * FROM (SELECT * FROM score WHERE c_id = '01' ORDER BY s_score DESC LIMIT 0,100 ) a UNION ALL SELECT * FROM (SELECT * FROM score WHERE c_id = '02' ORDER BY s_score DESC LIMIT 0,100) b UNION ALL SELECT * FROM (SELECT * FROM score WHERE c_id = '03' ORDER BY s_score DESC LIMIT 0,100) c; SELECT * FROM score ORDER BY c_id,s_score DESC