#1.请在stu表中将学号、姓名、入学成绩查询出来。
SELECt stuid,stuname,rx_score FROM stu;#2.请在stu表中将学号、姓名、入学成绩查询出来，并将查询列的名字用汉字显示。SELECt stuid AS 学号,stuname AS 姓名,rx_score AS 入学成绩 FROM stu;#3. 请在stu表中查询出所有男生的学号、姓名、入学成绩。SELECt stuid AS 学号,sex AS 性别,stuname AS 姓名,rx_score AS 入学成绩 FROM stu WHERe sex=‘男’;#4.请在stu表中查询出没有填电话号码的同学。SELECt stuname AS 姓名,phone AS 电话号码 FROM stu WHERe phone is NULL;#5.请在stu表中添加三位同学。其一学号为2020111，姓名张三，班级20计算机应用1，系部编号1001。其二学号为2020112，姓名张四，班级20计算机应用1，系部编号1001。第三位同学的所有信息都要输入，自己编写。INSERT stu(stuid,stuname,class,depid) VALUES (2020111,‘张三’,‘20计算机应用1’,1001);INSERT stu(stuid,stuname,class,depid) VALUES (2020112,‘张四’,‘20计算机应用1’,1001);INSERT stu VALUES (13,2020113,‘张五’,‘女’,‘1996-09-26’,500,17381430410,‘20计算机应用3’,1001,‘成绩良好’);#6.在stu表中查询入学成绩在450分以上的男生SELECt stuname AS 姓名,sex AS 性别,rx_score AS 入学成绩 FROM stu WHERe rx_score>=450 AND sex=‘男’;#7.在stu表中查询入学成绩在400-500之间电子信息系的学生SELECt stuname AS 姓名,class AS 电子信息系, depid AS 系部编号,rx_score AS 入学成绩 FROM stu WHERe rx_score BETWEEN 400 AND 500 AND depid=1001;#8.在stu表中查询入学成绩在400-500之间电子信息系的男生SELECt stuname AS 姓名,class AS 电子信息系, depid AS 系部编号,rx_score AS 入学成绩 FROM stu WHERe rx_score BETWEEN 400 AND 500 AND depid=1001;#9.在stu表中查询出系部编号为1005的同学的所有信息，并将他们的入学成绩增加50分。（原数据库中的成绩保持不变）SELECt *,rx_score+50 AS 新的成绩 FROM stu WHERe depid=1005;
