sql 目前只写出来第一题 第二题不会写代码

目前只写完第一题

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-- 创建XS表
CREATE TABLE [dbo].[XS](
[班级] nvarchar(50) NOT NULL, --非空
[姓名] nvarchar(50) NOT NULL,--非空
[语文] int check(语文 between 0 and 100) ,--0-100之间
[数学] int check(数学 between 0 and 100),--0-100之间
[外语] int check(外语 between 0 and 100),--0-100之间
[历史] int check(历史 between 0 and 100)--0-100之间
) ON [PRIMARY]
--添加数据
INSERT INTO XS
VALUES('1班','月月',85,100,85,90)
INSERT INTO XS
VALUES('3班','琪琪',80,90,80,80)
INSERT INTO XS
VALUES('2班','小云',90,90,90,80)
INSERT INTO XS
VALUES('1班','晨晨',88,99,88,76)
INSERT INTO XS
VALUES('3班','兰兰',90,98,90,85)
INSERT INTO XS
VALUES('1班','小一',54,58,61,50)
INSERT INTO XS
VALUES('1班','二牛',99,57,54,70)
INSERT INTO XS
VALUES('2班','微微',99,58,97,99)
INSERT INTO XS
VALUES('3班','小花',68,54,56,70)
INSERT INTO XS
VALUES('1班','彤彤',86,83,49,95)
INSERT INTO XS
VALUES('2班','啊沁',92,89,63,82)

alter table [XS] add [英语] int --添加英语列

ALTER TABLE [XS] DROP COLUMN [英语] --删除英语列