Question

我一直在尝试将我的MIS表格中的Quiz1，Quiz2，Exam1和Exam2字段的平均值加入到我的学生表中。

这是每张桌子的内容。

MIS包含以下字段：StudentID，QUIZ1，QUIZ2，EXAM1，EXAM2和ClassID

学生有专业，学生ID，学生参与

我想要完成的是两件事：

1。）将MIS表加入学生表 2.）获得测验1和2以及考试1和2的平均值。

预期结果是这样的：

专业---学生评论--- Quiz1Avg --- Quiz2Avg --- Exam1Avg --- Exam2Avg

到目前为止我尝试过：

Private Sub Query2_Enter(sender As Object, e As EventArgs) Handles Query2.Enter
        Dim DC As New OleDbConnection("provider=microsoft.ACE.oledb.12.0;data source=HogCountryUniversity.accdb")
        Dim DS As New DataSet()

        'Joined mis and students but don't know how to get the averages (working)'
        Dim DA As New OleDbDataAdapter("Select major, studstanding, quiz1, quiz2, exam1, exam2 from [mis] inner join [students] on [mis].studentid = [students].studentid", DC)

        'Display average of Quiz1 from mis table(working)'
        'Dim DA As New OleDbDataAdapter("Select classid, formatnumber(avg(quiz1),2) as [Quiz1Avg] from mis group by classid", DC)

        'Not working'
        'Dim DA As New OleDbDataAdapter("Select students.major, students.studstanding, quiz1, quiz2, exam1, exam2 from [mis] inner join on [students].studentid = [mis].studentid", DC)

        'Not working'
        'Dim DA As New OleDbDataAdapter("Select students.major, students.studstanding, avg(mis.quiz1) as [Quiz1Avg] from quiz1 mis inner join students on mis.studentid = students.studentid group by mis.classid", DC)

        DC.Open()
        DA.Fill(DS)

        DataGridView2.DataSource = DS.Tables(0).DefaultView()
        DC.Close()
    End Sub

我知道如何从一个表中获取一个字段的平均值并加入表格，但我不知道如何加入这两个表并获得上述字段的平均值。

我真的被卡住了，看了不同的堆栈溢出示例，但我仍然没有得到它。任何帮助/指示/推动/勺子喂养都非常感谢！

谢谢！

编辑：

我明白了！

 Dim DA As New OleDbDataAdapter("Select students.major, students.studstanding, formatnumber(avg(mis.quiz1),2) as Quiz1Avg, formatnumber(avg(mis.quiz2),2) as Quiz2Avg, formatnumber(avg(mis.exam1),2) as Exam1Avg, formatnumber(avg(mis.exam2),2) as Exam2Avg from students inner join mis on students.studentid = mis.studentid group by students.major, students.studstanding", DC)

VB2015：在加入表2后获取表1字段的平均值

0 个答案: