主题：如何产生不重复的随机数

换一种思路，如

Dim dt As DataTable = DataTables("表C")
dt.DeleteFor("")
Dim cnt As Integer = 999
Dim ids(cnt - 1) As Integer
For i As Integer = 0 To cnt -1
    ids(i) = i
Next
For i As Integer = 0 To cnt*2  '洗牌次数
    Dim id1 As Integer = rand.Next(0,cnt)
    Dim id2 As Integer = rand.Next(0,cnt)
    Dim vid As Integer = ids(id1)
    ids(id1) = ids(id2)
    ids(id2) = vid
Next
dt.StopRedraw()
Dim ks As Integer = Rand.Next(1000-300)
For i As Integer = 1 To 300
    Dim dr = dt.addnew
    dr("第一列")=ids(i+ks-1)
Next
dt.ResumeRedraw()