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DAO

DAO. 如果要用 簡單的 幾個字來涵蓋 VB資料庫的所 有功能, 那就只有DAO(Data Access Objects)了, DAO最早出現於微軟的Access資料庫, 後來 被VB3.0版引用, 近來則成為微軟相關產品 (包含VC++, Office系列)存取資料庫的標準. 物件 , 物件類別 , 集合物件. Database 物件類別 DBEngine 物件 Workspaces 集合物件. DBEngine 及Workspace物件.

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DAO

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  1. DAO 如果要用簡單的幾個字來涵蓋VB資料庫的所 有功能, 那就只有DAO(Data Access Objects)了, DAO最早出現於微軟的Access資料庫, 後來 被VB3.0版引用, 近來則成為微軟相關產品 (包含VC++, Office系列)存取資料庫的標準.

  2. 物件,物件類別,集合物件 Database 物件類別 DBEngine 物件 Workspaces 集合物件

  3. DBEngine及Workspace物件 Set db = DBEngine.Workspace(0).OpenDatabase( … )

  4. Database的五大物件 • TableDef物件 • QueryDef物件 • Recordset物件 • Relation物件 • Container物件

  5. Example for VisualBasic Dim db As Database Dim rs As Recordset Private Sub Form_Load Set db = DBEngine.Workspaces(0).OpenDatabase(App.Path + “\..\mdb\stock.mdb) Set rs = db.OpenRecordset(“股票行情表”) End Sub Private Sub Command_Click() ‘列出Recordset的所有資料錄 Dim S As String rs.MoveFirst List.Clear While Not rs.EOF S = “” For i=0 To rs.Fields.Count - 1 S = S & rs.Fields(i).Value & Chr(vbKeyTab) Next List.AddItem S rs.MoveNext Wend End Sub

  6. 結論 DAO所涵蓋的功能相當龐大, 當不是很清楚一 個DAO物件如和使用時, 除了查閱VB的說明 文件外, 你還可研究VisData的原始程式碼, 它 是一個功能相當齊全的資料庫工具程式, 且 幾乎所有DAO物件的使用範例都可在這個程 式的原始程式碼中找到.

  7. Reference • VB5與資料庫程式設計 王國榮著 1988,5

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