如何判断数据库字段的值是否为空？

AKIIscer 2004-11-22 10:03:25

Dim itemX As ListItem
ListView1.ListItems.Clear
rs.Open "select * from " + tv1.SelectedItem.Text, conn
For icol = 0 To rs.Fields.Count - 1
Set itemX = ListView1.ListItems.Add(, , icol + 1)
itemX.SubItems(1) = rs.Fields(icol).Name
itemX.SubItems(2) = rs.Fields(icol).Type
itemX.SubItems(3) = rs.Fields(icol).DefinedSize
Next icol
rs.Close

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AKIIscer 2004-11-22

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顺便问一下，主键，外键，索引怎么判断

AKIIscer 2004-11-22

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史留香，我请你吃饭，如果你在上海的话

tztz520 2004-11-22

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Dim itemX As ListItem
ListView1.ListItems.Clear
rs.Open "select * from " + tv1.SelectedItem.Text, conn
For icol = 0 To rs.Fields.Count - 1
if rs.Fields(icol).value & ""="" then'判断是空
debug.pring "这个值是空"
else
Set itemX = ListView1.ListItems.Add(, , icol + 1)
itemX.SubItems(1) = rs.Fields(icol).Name
itemX.SubItems(2) = rs.Fields(icol).Type
itemX.SubItems(3) = rs.Fields(icol).DefinedSize
end if
Next icol

leolan 2004-11-22

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//樓主意思是如何判斷字段是否允許為空嗎?
itemX.SubItems(4) = Iif(rs.Fields(icol).Attributes And adFldIsNullable , "Y", "N")

sunny8226 2004-11-22

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不过一般都是选不为空的吧？？
select * from 表 where *** is not null

sunny8226 2004-11-22

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select * from 表 where *** is null

foxphoenix 2004-11-22

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isnull(rs.×××)

wenhongL 2004-11-22

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up and 收藏了

AKIIscer 2004-11-22

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好的

leolan 2004-11-22

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'reference MS ADOX
Private Sub Form_Load()
Dim cn As ADODB.Connection
Dim cat As New ADOX.Catalog
Dim i As Integer

Set cn = New ADODB.Connection
With cn
.Provider = "Microsoft.Jet.OLEDB.4.0"
.CursorLocation = adUseClient
.ConnectionString = "Data Source=C:\Program Files\Microsoft Visual Studio\VB98\NWIND.MDB"
.Open
End With

Set cat.ActiveConnection = cn

For i = 0 To cat.Tables("Customers").Keys.Count - 1
'For i = 0 To cat.Tables("Customers").Indexes.Count - 1
Select Case cat.Tables("Customers").Keys(i).Type
Case adKeyPrimary
MsgBox cat.Tables("Customers").Keys(i).Columns(0).Name & " is Primary key."
Case adKeyUnique
MsgBox cat.Tables("Customers").Keys(i).Columns(0).Name & " is Unique key."
Case adKeyForeign
MsgBox cat.Tables("Customers").Keys(i).Columns(0).Name & " is Foreign key."
End Select
Next

cn.Close
Set cn = Nothing
Set cat = Nothing

End Sub

可惜我現在廣東,不過你這頓飯我可先記下了,下次有機會去上海的話再來跟你兌現啦..