如何对数据库进行添加、删除等操作？

例如在VB里建个窗体，有用户名，密码，确认密码添加，取消，点确定后，先从数据库里查询输入的用户名是否存在，若不存在切两次输的密码一致，

则在数据库表里添加该用户名和密码。有没有人把代码写出来啊？

万分感谢！！

Private Sub Command1_Click()

Dim mrc As ADODB.Recordset

txtsql = "select username from use where username='" & Trim(Text1.Text) & "'"

Set mrc = ExecuteSQL(txtsql)

If mrc.EOF = True Then

MsgBox " 用户名错误！", vbExclamation + vbOKOnly, "警告"

Text1.SetFocus

Text1.SelStart = 0

Text1.SelLength = Len(Text1.Text)

Exit Sub

End If

username = mrc.Fields(0)

txtsql = "select username from use where password='" & Trim(Text2.Text) & "'"

Set mrc = ExecuteSQL(txtsql)

If mrc.EOF = True Then

MsgBox " 密码错误！", vbExclamation + vbOKOnly, "警告"

Text2.SetFocus

Text2.SelStart = 0

Text2.SelLength = Len(Text2.Text)

Exit Sub

End If

MDIForm1.Show

Unload Me

End Sub

Private Sub Command2_Click()

Unload Me

End Sub

Private Sub Text1_KeyPress(KeyAscii As Integer)

If KeyAscii = 13 Then

Text2.SetFocus

End If

End Sub

Private Sub Text2_KeyPress(KeyAscii As Integer)

If KeyAscii = 13 Then

Command1.SetFocus

End If

End Sub