我的代码如下:
Dim conny As System.Data.SqlClient.SqlConnection
Dim cmdy As System.Data.SqlClient.SqlCommand
Dim dry As System.Data.SqlClient.SqlDataReader
conny = New System.Data.SqlClient.SqlConnection("Data Source=FJF;Initial Catalog=STInf;Integrated Security=True")
cmdy.CommandText = "Select * from CRoom"
cmdy.Connection = conn
conny.Open()
dry = cmdy.ExecuteReader
While dry.Read()
If dry("College") = Me.CbB7.Text Then
Me.CbB10.Items.Add(dr("CRname"))
End If
End While
dry.Close()
conny.Close()
按说应该没有什么错误,可怎么总是报如下警告呢:
变量“cmdy”在赋值前被使用,可能会在运行时导致空引用异常
大家有没有方法把这个警告消除阿,我刚开始学习还不是很会用,请大家多多指点
Dim conny As System.Data.SqlClient.SqlConnection
Dim cmdy As System.Data.SqlClient.SqlCommand
Dim dry As System.Data.SqlClient.SqlDataReader
conny = New System.Data.SqlClient.SqlConnection("Data Source=FJF;Initial Catalog=STInf;Integrated Security=True")
cmdy.CommandText = "Select * from CRoom"
cmdy.Connection = conn
conny.Open()
dry = cmdy.ExecuteReader
While dry.Read()
If dry("College") = Me.CbB7.Text Then
Me.CbB10.Items.Add(dr("CRname"))
End If
End While
dry.Close()
conny.Close()
按说应该没有什么错误,可怎么总是报如下警告呢:
变量“cmdy”在赋值前被使用,可能会在运行时导致空引用异常
大家有没有方法把这个警告消除阿,我刚开始学习还不是很会用,请大家多多指点
Dim cmdy As New System.Data.SqlClient.SqlCommand
conny.Open()
Dim cmdy As New System.Data.SqlClient.SqlCommand("Select * from CRoom", conny)
Dim dry As System.Data.SqlClient.SqlDataReader
dry = cmdy.ExecuteReader
While dry.Read()
If dry("College") = Me.CbB7.Text Then
Me.CbB10.Items.Add(dr("CRname"))
End If
End While
dry.Close()
conny.Close()