Question

我有关系数据库。每个学生都有不同的历史（一对多）。数据是正确的，但问题是学生信息在datagridview加载时变得重复。我使用DISTINCT函数但它不起作用。有人可以帮我弄清楚我的代码有什么问题。

加载时的vb.net代码

Using cmd As New SqlClient.SqlCommand("dbo.uspSELECTALL", cn)
    da.SelectCommand = cmd
    dt.Clear()
    da.Fill(dt)
    dgv1.RowTemplate.Height = 50
    dgv1.DataSource = dt
    For i As Integer = 0 To dgv1.Columns.Count - 1
        If TypeOf dgv1.Columns(i) Is DataGridViewImageColumn Then
            DirectCast(dgv1.Columns(i), DataGridViewImageColumn).ImageLayout = DataGridViewImageCellLayout.Stretch
        End If
    Next
End Using

存储过程代码

ALTER PROCEDURE [dbo].[uspSELECTALL]


AS
BEGIN

    SET NOCOUNT ON;

    SELECT  DISTINCT SI.StudentID,SI.Surname,SI.FirstName,SI.MiddleName, SI.StudAddress , 
            SI.BirthDay,SI.Gender, SI.Nationality, SI.BirthPlace,
            SI.TelNum,SI.SchoolWhereGraduated , 
            SI.DatesWhenGraduated, SI.SchoolLastAttended,
            SI.Note,SI.StudImage,
            PI.Father_FirstName,PI.Father_LastName,
            PI.Father_MI,PI.Father_Occupation, 
            PI.Father_TelNUm, PI.Mother_FirstName, PI.Mother_LastName,
            PI.Mother_MI,PI.Mother_Occupation,PI.Mother_TelNum,
            PI.Contact_FirstName,PI.Contact_LastName,PI.Contact_MI,
            PI.Contact_Mobile,PI.Contact_TelNum,PI.Contact_Address,
            SH.SchoolYear,SH.Levels,SH.Section,SH.DateEnrolled

            FROM StudentInformation SI 
            JOIN StudentHistory SH  
                ON SI.StudentID = SH.StudentID
            JOIN ParentInformation PI
                ON PI.ParentID = SI.ParentID

END

Answer 1

如果您希望AlertDialog.Builder alertDialog = new AlertDialog.Builder(this); alertDialog.setCancelable(false);中的节目仅区分学生的身份，则然后你需要使用另一个查询如果学生有多个历史记录，则您当前的查询总是返回每个学生的多行。一种方法是从DataGridView语句中删除表StudentHistory的所有列，并在查询中保留SELECT个关键字。

DISTINCT

另一种方法是过滤您的查询填充的SELECT DISTINCT SI.StudentID,SI.Surname,SI.FirstName,SI.MiddleName, SI.StudAddress , SI.BirthDay,SI.Gender, SI.Nationality, SI.BirthPlace, SI.TelNum,SI.SchoolWhereGraduated , SI.DatesWhenGraduated, SI.SchoolLastAttended, SI.Note,SI.StudImage, PI.Father_FirstName,PI.Father_LastName, PI.Father_MI,PI.Father_Occupation, PI.Father_TelNUm, PI.Mother_FirstName, PI.Mother_LastName, PI.Mother_MI,PI.Mother_Occupation,PI.Mother_TelNum, PI.Contact_FirstName,PI.Contact_LastName,PI.Contact_MI, PI.Contact_Mobile,PI.Contact_TelNum,PI.Contact_Address FROM StudentInformation SI JOIN StudentHistory SH ON SI.StudentID = SH.StudentID JOIN ParentInformation PI ON PI.ParentID = SI.ParentID。

DataTable

Using cmd As New SqlClient.SqlCommand("dbo.uspSELECTALL", cn) da.SelectCommand = cmd dt.Clear() da.Fill(dt) dgv1.RowTemplate.Height = 50 'Filtering for distinct rows Dim view As New DataView(GetData()) Dim distinctColumnNames As String() = { "StudentID", "Surname", "FirstName", "MiddleName", "StudAddress" ' and so on } Dim distinctValues As DataTable = view.ToTable(True, distinctColumnNames) dgv1.DataSource = distinctValues 'Your other code End Using如果第一个参数为view.ToTable(True, distinctColumnNames)，那么将仅包含基于列名的不同行

记录在vb.net中变得重复

1 个答案: