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我有一个错误,无法删除(在我已经复制的代码的末尾)。我读了它,并且明白了说的是什么,但是我在该行中使用的两个对象既是实例化的,也是之前使用的。我使用了断点,在我看来,它们都有值,它们与null不同。例如,修改或删除操作就像他们应该执行的一样(我没有在这里复制它们)。你可以帮我吗。谢谢!未将对象引用设置为对象的实例VB
Public Class Form1
Dim dataSet As DataSet
Dim dataAdapterStudenti As New System.Data.SqlClient.SqlDataAdapter
Dim dataAdapterSectii As New SqlClient.SqlDataAdapter
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Try
con.Open()
dataSet = New DataSet
Dim insertStudenti As New SqlClient.SqlCommand
insertStudenti.CommandType = CommandType.Text
insertStudenti.CommandText = "insert into studenti (cods,grupa,nume,datan,nrmatricol) values (@cods,@grupa,@nume,@datan,@nrmatricol)"
insertStudenti.Connection = con
insertStudenti.Parameters.Clear()
p = insertStudenti.Parameters.Add("@cods", SqlDbType.Int, 4, "cods")
p.SourceVersion = DataRowVersion.Current
p = insertStudenti.Parameters.Add("@nrmatricol", SqlDbType.Int, 4, "nrmatricol")
p.SourceVersion = DataRowVersion.Current
p = insertStudenti.Parameters.Add("@nume", SqlDbType.VarChar, 40, "nume")
p.SourceVersion = DataRowVersion.Current
p = insertStudenti.Parameters.Add("@grupa", SqlDbType.Int, 4, "grupa")
p.SourceVersion = DataRowVersion.Current
p = insertStudenti.Parameters.Add("@datan", SqlDbType.DateTime, 4, "datan")
p.SourceVersion = DataRowVersion.Current
dataAdapterStudenti.InsertCommand = insertStudenti
dataAdapterStudenti.Fill(DataSet, "studenti")
DataSet.Tables("studenti").Constraints.Clear()
DataSet.Tables("studenti").Constraints.Add("PK_nrmatricol", DataSet.Tables("studenti").Columns("nrmatricol"), True)
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub
Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
If (Verifica() And EsteNrMatricolUnic()) Then
Dim dr As DataRow
dr = dataSet.Tables("studenti").NewRow()
dr("cods") = CInt(txtCodS.Text)
dr("nrmatricol") = CInt(txtNrMatricol.Text)
dr("nume") = txtNume.Text
dr("grupa") = txtGrupa.Text
dr("datan") = pickerDataNasterii.Value
Try
dataSet.Tables("stdenti").Rows.Add(dr) 'here is the error
dataAdapterStudenti.Update(dataSet, "studenti")
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End If
End Sub
End Class
我正在看它过去三天。这太疯狂了 :)))))) – Tamango