根据组合框值在文本框中显示多个值

Question

我有一张桌子 - tblMAIN
我有 4 个 ID 字段 - mainID、FatherID、MotherID 和 FullName
1 个表格 - frmMAIN
1 个组合框 - cboMAIN
2 个文本框 - txtFATHER、txtMOTHER

我正在尝试在 VBA 中编写一条 SQL 语句，该语句将在组合框 cboMAIN 中选择一条记录，并通过该选择填充两个文本框。

罗伯特在 cboMAIN 中被选中，罗伯特的 MainID 为 20
Robert 的母亲是 Ruth，她的 MainID 为 30
罗伯特父亲的 MainID 是 40

所以在 txtFather 中它将显示记录 40 / FullName，在 txtMother 中它将显示记录 MainID30 的 FullName。

我想添加文本字段并显示 Ruth 的母亲和 Robert 的父亲的父亲。

这是我的一个想法，但不知道下一步该做什么。

Dim sqlME As String
Dim sqlFATHER As String
Dim db As Database
Dim rs As DAO.Recordset

sqlFATHER = "SELECT * FROM tblMAIN WHERE MainID = " & Forms![MAIN]![cboMAIN] & ";"

'AND NOT SURE WHAT I NEED TO DO HERE!

 Set db = CurrentDb
 Set rs = db.OpenRecordset(sqlFATHER)
 Me.txtFather.Value = rs!FullName
 Set rs = Nothing
 Set db = Nothing

Answer 1

UNBOUND 文本框的 VBA 设置值将为每条记录显示相同的值。

这些数据本质上是递归的，Access SQL 不容易操作递归数据。其他数据库平台有实用性可以更好地处理。

构建一个名为 qryAncestors 的自联接查询对象：

SELECT tblMain.mainID, tblMain.FullName, tblMain_1.FullName AS Father, 
tblMain_2.FullName AS Mother, tblMain_3.FullName AS PGFather, 
tblMain_4.FullName AS PGMother, tblMain_5.FullName AS MGFather, tblMain_6.FullName AS MGMother
FROM tblMain AS tblMain_6 
RIGHT JOIN (tblMain AS tblMain_5 
RIGHT JOIN (tblMain AS tblMain_4 
RIGHT JOIN (tblMain AS tblMain_3 
RIGHT JOIN (tblMain AS tblMain_2 
RIGHT JOIN (tblMain AS tblMain_1 
RIGHT JOIN tblMain 
ON tblMain_1.mainID = tblMain.FatherID) 
ON tblMain_2.mainID = tblMain.MotherID) 
ON tblMain_3.mainID = tblMain_1.FatherID) 
ON tblMain_4.mainID = tblMain_1.MotherID) 
ON tblMain_5.mainID = tblMain_2.FatherID) 
ON tblMain_6.mainID = tblMain_2.MotherID;

然后使用该查询的选项：

1. reference 查询作为组合框 RowSource 然后文本框 ControlSource 按索引引用组合框列 =[cboMain].Column(2)

2. 文本框ControlSource使用DLookup()表达式，如：
   =DLookUp("Father", "qryAncestors", "mainID=" & mainID)

3. 文本框ControlSource调用VBA自定义函数返回值，如：
   =GetAncestor(mainID, "Father")

Function GetAncestor(intID As Integer, strAnc As String)
GetAncestor = DLookUp(strAnc, "qryAncestors", "mainID=" & intID)
End Function

如果您想超越祖父母达到任何水平，方法就必须完全不同。递归过程很棘手。返回祖先全名的函数可能是：

Function GetAncestor(intID As Integer, intGen As Integer, strParent As String)
Dim x As Integer
GetAncestor = intID
For x = 1 To intGen
    GetAncestor = DLookup(strParent, "tblMain", "mainID=" & Nz(GetAncestor,0))
Next
GetAncestor = DLookup("FullName", "tblMain", "mainID=" & Nz(GetAncestor,0))
End Function

获取特定世代的祖先，调用函数：GetAncestor(mainID, 1, "MotherID")