功能 在表trans_data中查询字段roadname中每个值出现的次数语句 SELECT roadname, count(*)FROM trans_data GROUP BY roadname
功能 在表trans_data中查询字段roadname中每个值出现的次数(并排序)语句 select roadname, count(*)from trans_data GROUP BY roadname ORDER BY 'count'
功能 在表trans_data中查询字段roadname、time,并按time排序输出语句 SELECT roadname, 'time'FROM trans_dataWHERE (roadname = '碧新路')ORDER BY time
功能 将字段roadname和dirction合并后再做统计语句 SELECT road, count(*) FROM (SELECT (roadname || dirction) AS road,* FROM 'trans_data' ) AS new_trans_data GROUP BY road
功能展示生成的新表,并显示展示条数语句SELECT *FROM (SELECT (roadname || ' (' || dirction||')') AS road,* FROM 'trans_data' ) AS new_trans_data LIMIT 100
功能生成新表,并查询新表中时间介于两个时刻间的结果语句SELECT *FROM (SELECT (roadname || ' (' || dirction||')') AS road,* FROM 'trans_data' ) AS new_trans_dataWHERE time BETWEEN '2' AND '2'ORDER BY time
功能生成新表,并查询新表中时间介于两个时刻间的结果语句SELECT *FROM (SELECT (roadname || ' (' || dirction||')') AS road,* FROM 'trans_data' ) AS new_trans_dataWHERE '2' <= time AND time <= '2'ORDER BY time
功能查询某字段有多少不同的值语句SELECT distinct(new_trans_data.road)FROM (SELECT (roadname || ' (' || dirction||')') AS road,* FROM 'trans_data' ) AS new_trans_dataORDER BY new_trans_data.road
求选修了高等数学的学生学号和姓名。
求1号课程的成绩高于张三的学生学号和成绩。
求其他系中比计算机系某一学生年龄小的学生。
求其他系中比计算机系学生年龄都小的学生。
求选修了2号课程的学生姓名。
求没有选修2号课程的学生姓名。(可用not exists或not in实现,比较若用其他方法实现,结果有何不同)
其他方法