10.27周测

student表

score表

--从student表查询所有学生的学号（id）、姓名（name）和院系（department）的信息SELECT id,name,department FROM student;--从student表中查询年龄18~22岁的学生信息SELECT id,name,sex,2017-birth AS age,department,addressFROM studentWHERE 2017-birth BETWEEN  18 AND 22;--从student表中查询每个院系有多少人 SELECT department, COUNT(id) FROM student GROUP BY department;--从score表中查询每个科目的最高分SELECT c_name,MAX(grade) FROM score GROUP BY c_name;--查询李四的考试科目（c_name）和考试成绩（grade）SELECT c_name, gradeFROM studentLEFT JOIN score ON score.stu_id=student.idWHERE name= '李四';--用连接的方式查询所有学生的信息和考试信息SELECT student.id,name,sex,birth,department,address,c_name,gradeFROM student,scoreWHERE student.id=score.stu_id;--计算每个学生的总成绩SELECT student.id,name,SUM(grade) FROM student,scoreWHERE student.id=score.stu_idGROUP BY id;--计算每个考试科目的平均成绩SELECT c_name,AVG(grade) FROM score GROUP BY c_name;--查询计算机成绩低于95的学生信息SELECT * FROM studentLEFT JOIN scoreON student.id = score.stu_idWHERE c_name='计算机' AND grade < 95;--查询同时参加计算机和英语考试的学生的信息SELECT *  FROM studentWHERE id = ANY( SELECT stu_id FROM scoreWHERE stu_id IN (SELECT stu_id FROMscore WHERE c_name=  '计算机')AND c_name= '英语' );--将计算机考试成绩按从高到低进行排序SELECT stu_id, gradeFROM score WHERE c_name= '计算机'ORDER BY grade DESC;--从student表和score表中查询出学生的学号，然后合并查询结果SELECT id  FROM studentUNIONSELECT stu_id  FROM score;--查询姓张或者姓王的同学的姓名、院系和考试科目及成绩SELECT name, department, c_name, gradeFROM studentLEFT JOIN scoreON score.stu_id = student.idWHERE name LIKE '张%' OR name LIKE '王%'--查询都是湖南的学生的姓名、年龄、院系和考试科目及成绩SELECT name, 2017-birth, department, c_name, gradeFROM student LEFT JOIN scoreON score.stu_id = student.idWHERE address LIKE '湖南%' ;