The TreeView control is more used in the program process. Correctly mastering and using this control, you can express data from hierarchical relationships. In the database application system, we can display the tree structure with TreeView, such as displaying the directory tree, displaying class information, etc., has an important role.
See an actual problem below: There are many classes every year, indicating these data levels.
Database: Access
Table: Test
Field: BH (class number, text, primary key), NJ (grade, text)
Function: Data is expressed in hierarchical relationships
Test Data:
BH
NJ
41020
2001
41021
2001
41025
2003
41026
2003
41027
2003
41028
2003
Add TreeView control, 2 buttons
Two buttons used two ways to display data. However, the second method is significantly better than the first.
Can see code carefully
'Quote Microsoft ActiveX Data Object 2.x Library
DIM NDDATA AS NODE
DIM CNN As Adodb.Connection
DIM RS1 AS New Adodb.Recordset
DIM RS2 As New AdoDB.Recordset
Private submmand1_click ()
ON Error ResMe next
Set nddata = TreeView1.nodes.add (, "db", "class information")
nddata.expanded = true
DIM INTCOUNT AS INTEGER
DIM INTTABLE AS INTEGER
DIM INTFIELD AS INTEGER
DIM INTFN AS INTEGER
RS1.Open "SELECT NJ from Test Group By NJ", CNN, 1, 3
INTTABLE = RS1.Recordcount
Do While INTTABLE <> intcount
Set nddata = TreeView1.nodes.add ("db", TVwchild, "f" & rs1.fields ("nj"), RS1.Fields ("nj"))
rs2.open "SELECT BH, NJ from test where nj = '" & r1.fields ("nj") & "'", CNN, 1, 3
INTFIELD = rs2.Recordcount
IF Intfield <> 0 THEN
INTFN = 0
Do While Intfield <> intfn
Set nddata = TreeView1.nodes.Add ("f" & rs1.fields ("nj"), TVWchild, "S" & rs2.fields ("BH"), RS2.Fields ("BH"))
RS2.MOVENEXT
INTFN = INTFN 1
Loop
END IF
RS2.Close
RS1.MOVENEXT
INTCOUNT = INTCOUNT 1
Loop
Rs1.close
End Sub
'The second method
Private sub fascist2_click ()
ON Error ResMe next
Set nddata = TreeView1.nodes.add (, "db", "class information") nddata.expanded = true
RS1.Open "Select * from test", CNN, 1, 3
Do While Not Rs1.eof
IF CA <> rs1.fields ("nj") THEN
Set nddata = TreeView1.nodes.add ("db", TVwchild, "f" & rs1.fields ("nj"), RS1.Fields ("nj"))
Ca = rs1.fields ("bb")
END IF
Set nddata = TreeView1.Nodes.Add ("f" & rs1.fields ("nj"), TVWchild, "S" & rs1.fields ("BH"), RS1.Fields ("BH"))
RS1.MOVENEXT
Loop
Rs1.close
End Sub
Private sub flow_load ()
Set cnn = new adodb.connection
CNN.Open "provider = microsoft.jet.Oledb.4.0; Data Source = f: / 9cbs_vb / database / treeview Node Add / 1/test.mdb"
End Sub
Private Sub Form_Unload (Cancel AS Integer)
Set con = Nothing
End Sub
