As for planting trees, 90% of people will not plant infinite-level trees, and 80% of people will not plant first-level trees.
Today, I will teach you how to plant first-level trees and infinite trees.
Let’s take a look at the background table first. treedata1, id is an auto-incrementing primary key.
1. Make a form
2. Use MSSQLHelper to obtain data in form LOAD
DO setenv
LOCAL oDBSQLHelper,nRow,oca
& amp; & amp;Member category table
TEXT TO lcSQLCmd NOSHOW TEXTMERGE
SELECT * FROM treedata1
ENDTEXT
oDBSQLHelper=Newobject("MSSQLHelper","MSSQLHelper.prg")
nRow=oDBSQLHelper.SQLQuery(lcSQLCmd,"treedata1")
IF nRow<1
Messagebox(oDBSQLHelper.errmsg,0 + 16,Thisform.Caption)
Return.F.
Endif
3. Set form properties
Set the attribute value of the tree control as shown in the figure, displayfield=name, datafield=id
qiyu_treeview control property description
| Attribute name | Default | Description |
| mainalias | Bound table | |
| displayfield | Display field | |
| datafield | Bind value field | |
| value | Control selected value | |
| isdisplaykey | Whether to display the value of the value field | |
| fatherfield | Parent field (for multi-level trees) |
The two text box controls can be bound to treedata1.id and treedata1.name respectively.
Donodeclick of qiyu_treeview1 refreshes the form
LPARAMETERS node thisform.Refresh()
Let’s run it again
If the operation is successful, click on any tree node and the control on the right will change.
How to plant infinite trees
Backend table structure minimalist
There is only one more field than the first-level tree
Just set one more fatherkey to fid in the attributes of qiyu_treeview1
The other controls have the same settings, and an additional combo box is added to display the contents of fid.
Combo box settings
Set the combo box to read-only and prevent modification.
The form’s load event loads data
DO setenv
LOCAL oDBSQLHelper,nRow,oca
& amp; & amp;Member category table
TEXT TO lcSQLCmd NOSHOW TEXTMERGE
SELECT * FROM treedata
ENDTEXT
oDBSQLHelper=Newobject("MSSQLHelper","MSSQLHelper.prg")
nRow=oDBSQLHelper.SQLQuery(lcSQLCmd,"treedata")
IF nRow<1
Messagebox(oDBSQLHelper.errmsg,0 + 16,Thisform.Caption)
Return.F.
Endif
*--For combo box
SELECT * FROM treedata INTO CURSOR treedata2
After running it, do you think it is easy to plant trees?
Mao Mao’s inner thoughts
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