求助这个SQL语句怎么写

1、创建数据库表exam

创建数据库表exam

2、数据库表插入记录

数据库表插入记录

3、编写查询SQL语句并执行

SELECT

  c_number 学号,

  c_name 姓名,

  AVG(c_grade) 平均成绩

FROM

  exam

GROUP BY

  c_number,

  c_name

HAVING

  AVG(c_grade) >80

编写SQL语句并执行

Create table  EXAM_USER

( 

  USER_ID varchar(7) primary key,

  USER_NAME varchar(10) not null, 

  USER_PWD  varchar(20) not null, 

  SEX char(2) check(SEX='男'or SEX='女'), 

  AGE int check(Sage between 15 and 45) 

 ）

先在程序中添加对Microsoft

ADO

Ext

2.8的引用，然后

1234567891011121314151617181920212223string db = Application.StartupPath + @"\Exam.mdb"string connstr = string.Format("Provider=Microsoft.Jet.OLEDB.4.0Data Source={0}", db)ADOX.Catalog catalog = new Catalog()catalog.Create(connstr)//创建数据库using (OleDbConnection connection = new OleDbConnection(connstr)){connection.Open() OleDbCommand cmd = connection.CreateCommand() cmd.CommandText = "CREATE TABLE student(Num AUTOINCREMENT,Name TEXT(50),Birthday DateTime,CONSTRAINT table1_PK PRIMARY KEY(Num))" cmd.ExecuteNonQuery()//创建表//插入三条数据string insert = "insert into student(Name,Birthday) values('{0}',#{1}#)" cmd.CommandText = string.Format(insert,"MARY", "2016-02-14 22:04:36") cmd.ExecuteNonQuery() cmd.CommandText = string.Format(insert, "PATRICIA", "2015-02-20 18:05:27") cmd.ExecuteNonQuery() cmd.CommandText = string.Format(insert, "LINDA", "2013-10-18 05:03:28") cmd.ExecuteNonQuery() connection.Close()}//关闭数据库System.Runtime.InteropServices.Marshal.FinalReleaseComObject(catalog.ActiveConnection)System.Runtime.InteropServices.Marshal.FinalReleaseComObject(catalog)

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