VB6-操作数据库

平常搞数据库操作多了就想把经常用的内容放在一起，我也懒，在一本书里的工程例子挑了一个bas，修修改改，凑合这用吧。

 Public strCnn As String  '数据库连接字符串
 Public AdoCnn As ADODB.Connection '数据库连接
 Public IsConnect As Boolean  '判断是否连接

 Private Sub Connect() '连接数据库
     On Error GoTo Err:
     If IsConnect = True Then  '如果连接标记为真，则返回。否则会出错
         Exit Sub
     End If

     Set AdoCnn = New ADODB.Connection '关键New用于创建新对象cnn
     With AdoCnn
         .ConnectionString = strCnn
         .ConnectionTimeout =
         .Open
     End With
     IsConnect = True  '设置连接标记，表示已经连接到数据库
     Exit Sub
 Err:
     If Err = - Then
         Set Cnn = Nothing
         MsgBox Err.Description & "请检查数据库配置!", vbOKOnly + vbInformation, "Connect"
     Else
         MsgBox Err.Description & "请检查数据库配置!", vbExclamation, "Connect"
     End If

 End Sub

 Public Sub Disconnect() '断开与数据库的连接
     Dim rc As Long
     If IsConnect = False Then Exit Sub '如果连接标记为假，标明已经断开连接，则直接返回
     AdoCnn.Close  '关闭连接

     Set AdoCnn = Nothing
     IsConnect = False
 End Sub

 Public Sub DB_Connect() '使用Connect_Num控制数据库连接
     Connect_Num = Connect_Num +
     Connect
 End Sub

 Public Sub DB_Disconnect()
     If Connect_Num >= CONNECT_LOOP_MAX Then
         Connect_Num =
         Disconnect
     End If
 End Sub

 Public Sub DBapi_Disconnect() '强制关闭api方式访问的数据库，计数器复位
     Connect_Num =
     Disconnect
 End Sub

 Public Sub ExecSql(ByVal TmpSql As String)   '执行数据库操作语句
     On Error GoTo Err:
     Dim cmd As New ADODB.Command  '创建Command对象cmd
     DB_Connect    '连接到数据库
     Set cmd.ActiveConnection = AdoCnn  '设置cmd的ActiveConnection属性，指定与其关联的数据库连接
     cmd.CommandText = TmpSql  '设置要执行的命令文本
     cmd.Execute
     Set cmd = Nothing
     DB_Disconnect
     Exit Sub
 Err:
     MsgBox Err.Description, , "ExecSql"
 End Sub

 Public Function QuerySql(ByVal TmpSql As String) As ADODB.Recordset '执行数据库查询语句
     On Error GoTo Err:
     Dim rst As New ADODB.Recordset
     DB_Connect    '连接到数据库
     If IsConnect = False Then Exit Function
     Set rst.ActiveConnection = AdoCnn    '设置rst的ActiveConnection属性，指定与其关联的数据库连接
     rst.CursorType = adOpenKeyset
     rst.LockType = adLockOptimistic   '设置锁定类型
     rst.Open TmpSql    '打开记录集
     Set QuerySql = rst    '返回记录集
     Exit Function
 Err:
     MsgBox Err.Description, , "QuerySql"
 End Function

 Public Function GetFieldValue(FieldValue As Variant) As String
     GetFieldValue = IIf(Not IsNull(FieldValue), FieldValue, "")
 End Function