急！请教一道数据库考题

我这里给了参考的答案，但是我的愿望和一楼是一样的，希望学习这种东西是自己的刻苦努力，而不是投机取巧，加油。

1.

select c.课程名称,c.任课教师

from 成绩 a,课程 b,学生 c

where a.课程号=b.课程号 and a.学号=c.学号

and c.学号=S3

2.

select 课程号，课程名称

from 课程

where 任课教师='LIU'

3.

select a.姓名

from 学生 a,成绩 b,课程 c

where a.学号=b.学号 and b.课程=c.课程

and a.性别='女' and c.任课教师='LIU'

group by a.姓名

having count(a.姓名)>=1

4.

select 学号，姓名，班级

from 学生

where 学号 not in(

select distinct 学号

from 成绩

)

'使用方法，在打开窗体时用opendb即可，关闭用closedb,数据库文件你修改dbname变量'表 *** 作 打开 openrs 1,"select * from ..."关闭 closers 1我写了四个表 *** 作变量，1234，你自己看着理解，你要会SQl语句，要不这也没有什么用。'数据库连接：放在一个模块里里面

Public Const DBName = "FoxData.mdb"

Public Const DBpass = ""

Public conn As New ADODB.Connection

Public Rs1 As New ADODB.Recordset

Public Rs2 As New ADODB.Recordset

Public Rs3 As New ADODB.Recordset

Public Rs4 As New ADODB.RecordsetPublic Sub OpenDB()

Dim DBpath As String

DBpath = App.Path + "\" + DBName

conn.Open "provider=Microsoft.Jet.oledb.4.0data source=" &DBpath &"Jet OLEDB:Database Password=" &DBpass &""

End Sub

'******************************************

'关闭数据库

Public Sub CloseDB()

On Error Resume Next

conn.Close

Set conn = Nothing

End SubPublic Sub OpenRs(ByVal RsNum As Integer, ByVal RsSql As String)

Select Case RsNum

Case 1: Rs1.Open RsSql, conn, adOpenKeyset, adLockPessimistic

Case 2: Rs2.Open RsSql, conn, adOpenKeyset, adLockPessimistic

Case 3: Rs3.Open RsSql, conn, adOpenKeyset, adLockPessimistic

Case 4: Rs4.Open RsSql, conn, adOpenKeyset, adLockPessimistic

End SelectEnd Sub

Public Sub CloseRs(ByVal RsNum As Integer)

Select Case RsNum

Case 1: Rs1.Close: Set Rs1 = Nothing

Case 2: Rs2.Close: Set Rs2 = Nothing

Case 3: Rs3.Close: Set Rs3 = Nothing

Case 4: Rs4.Close: Set Rs4 = Nothing

End Select

End Sub

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