Oracle/MySQL/SQL Server查询前N条数据

需求：查询年龄小于20岁分数排名最靠前的五名学生

1. Oracle

   SELECT ID, NAME, AGE, SCORE
     FROM (SELECT ID, NAME, AGE, SCORE
   	  FROM T_STUDENT
   	 WHERE AGE < 20
   	 ORDER BY SCORE DESC)
    WHERE ROWNUM <= 5
    ORDER BY ROWNUM ASC

   
   
   
2. MySQL

   SELECT ID, NAME, AGE, SCORE
     FROM T_STUDENT
    WHERE AGE < 20
    ORDER BY SCORE DESC
    LIMIT 0,5

   
   
   
3. SQL Server

   SELECT TOP 5
      ID, NAME, AGE, SCORE
     FROM T_STUDENT
    WHERE AGE < 20
    ORDER BY SCORE DESC