clsdb.cls

这是一个选课系统

VERSION 1.0 CLASS
BEGIN
  MultiUse = -1  'True
  Persistable = 0  'NotPersistable
  DataBindingBehavior = 0  'vbNone
  DataSourceBehavior  = 0  'vbNone
  MTSTransactionMode  = 0  'NotAnMTSObject
END
Attribute VB_Name = "ClsDB"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = True
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Option Explicit
'数据库连接
Public conn As New ADODB.Connection

'表明当前数据库的连接状态:False－未连接；True－已连接
Public dbStatus As Boolean


Public Function openDB() As Boolean
   
    On Error GoTo errHandler
    
    conn.Open sqlstring
    
    '如果出现连接错误
'    MsgBox Err.Description: GoTo errHandler
    If Err.Number <> 0 Then
      openDB = False
    Else
      openDB = True
    Exit Function
End If
errHandler:
    openDB = False
    
End Function

Public Function closeDB() As Integer
    conn.Close

    dbStatus = False
End Function


Public Function ExecuteSQL(ByVal sql As String, MsgString As String) As ADODB.Recordset
'executes SQL and returns Recordset
   Dim cnn As ADODB.Connection
   Dim rst As ADODB.Recordset
   Dim sTokens() As String
   
   On Error GoTo ExecuteSQL_Error
   
   sTokens = Split(sql)
   Set cnn = New ADODB.Connection
   cnn.Open sqlstring
   If InStr("INSERT,DELETE,UPDATE", UCase$(sTokens(0))) Then
      cnn.Execute sql
      MsgString = sTokens(0) & " query successful"
   Else
      Set rst = New ADODB.Recordset
      rst.Open Trim$(sql), cnn, adOpenKeyset, adLockOptimistic
      'rst.MoveLast     'get RecordCount
      Set ExecuteSQL = rst
      MsgString = "查询到" & rst.RecordCount & " 条记录 "
   End If
ExecuteSQL_Exit:
   Set rst = Nothing
   Set cnn = Nothing
   Exit Function
   
ExecuteSQL_Error:
   MsgString = "查询错误: " & Err.Description
   Resume ExecuteSQL_Exit
End Function