vb关于全局变量的问题

[tim104]

我想用vb做个简单的连接数据库的软件，是连接sqlserver的，我现在的代码是如下：
Dim conn As ADODB.Connection
Dim rs As ADODB.Recordset

Private Sub Command1_Click()
rs.Open "select sc.*,course.cname from course,sc where sc.cno=course.cno and sno=" & sno.Text, conn, adOpenStatic, adLockReadOnly, adCmdText
fsno.Enabled = False
End Sub

Private Sub Form_Load()
conn.ConnectionString = "DSN=LocalServer;uid=sa;pwd=1234;DATABASE=mytdb"
conn.ConnectionTimeout = 30
conn.Open
End Sub

Private Sub Form_Unload(Cancel As Integer)
conn.Close
End Sub

运行是他说我的Form_Load()函数的 conn为未知变量，当我把Form_Load()的代码改为
Dim conn As ADODB.Connection
conn.ConnectionString = "DSN=LocalServer;uid=sa;pwd=1234;DATABASE=mytdb"
conn.ConnectionTimeout = 30
conn.Open
时就可以正常连接，但是如果是这样设的话，我其他的函数就不能引用conn这个变量，请高手指教

[szjhxu]

将Form_Load代码改写为:

Private Sub Form_Load()
Set conn = New ADODB.Connection '增加此句,目的是生成一个connection对象
conn.ConnectionString = "DSN=LocalServer;uid=sa;pwd=1234;DATABASE=mytdb"
conn.ConnectionTimeout = 30
conn.Open
End Sub

[CPLiu]

把最开始的Dim conn As ADODB.Connection改为
Dim conn As New ADODB.Connection

[cbzdream]

Dim conn As ADODB.Connection－－－－改为Dim conn new As ADODB.Connection
Dim rs As ADODB.Recordset

[taoheping]

变量没有实例化

[ChumpKlutz]

有两种方法:
(1)在声明时就实例化:Dim conn As New Adodb.Connection
(2)先声明后实例: Dim conn as Adodb.Connection
Set conn=new Adodb.Connection

[zhangzhijian]

hehe,都已经说了,只有帮你ding把了