Question

我通过SQL语句进行了查询。我得到了正确的结果，每个结果在查询中重复4次。我很困惑为什么我得到4份相同的结果。

以下是表单的代码：

Dim strTables As String
Private Sub btnFollowUpQs_Click()
    If (btnFollowUpQs.Value = True) Then
        Set db = CurrentDb()
        Set rs = db.OpenRecordset(btnFollowUpQs.Caption)
        Dim fld As DAO.Field
        For Each fld In rs.Fields
            Me.lstVariablesFollowUpQs.AddItem (fld.Name)
        Next
        Set fld = Nothing
        db.Close
        strTables = strTables + "," + btnFollowUpQs.Caption
    Else
        lstVariablesFollowUpQs.RowSource = ""
        strTables = Replace(strTables, "," + btnFollowUpQs.Caption, "")
    End If
    Debug.Print strTables
End Sub

Private Sub btnBaseline_Click()
    If (btnBaseline.Value = True) Then
        Set db = CurrentDb()
        Set rs = db.OpenRecordset(btnBaseline.Caption)
        Dim fld As DAO.Field
        For Each fld In rs.Fields
            Me.lstVariablesBaseline.AddItem (fld.Name)
        Next
        Set fld = Nothing
        db.Close
        strTables = strTables + "," + btnBaseline.Caption
    Else
        lstVariablesBaseline.RowSource = ""
        strTables = Replace(strTables, "," + btnBaseline.Caption, "")
    End If
        Debug.Print strTables
End Sub

Private Sub btnTreatments_Click()
    If (btnTreatments.Value = True) Then
        Set db = CurrentDb()
        Set rs = db.OpenRecordset(btnTreatments.Caption)
        Dim fld As DAO.Field
        For Each fld In rs.Fields
            Me.lstVariablesTreatments.AddItem (fld.Name)
        Next
        Set fld = Nothing
        db.Close
        strTables = strTables + "," + btnTreatments.Caption
    Else
        lstVariablesTreatments.RowSource = ""
        strTables = Replace(strTables, "," + btnTreatments.Caption, "")
    End If
        Debug.Print strTables
End Sub

Private Sub btnQuestionnaires_Click()
    If (btnQuestionnaires.Value = True) Then
        Set db = CurrentDb()
        Set rs = db.OpenRecordset(btnQuestionnaires.Caption)
        Dim fld As DAO.Field
        For Each fld In rs.Fields
            Me.lstVariablesQuestionnaires.AddItem (fld.Name)
        Next
        Set fld = Nothing
        db.Close
        strTables = strTables + "," + btnQuestionnaires.Caption
    Else
        lstVariablesQuestionnaires.RowSource = ""
        strTables = Replace(strTables, "," + btnQuestionnaires.Caption, "")
    End If
        Debug.Print strTables
End Sub

Private Function createSQL(ByRef lstCtrl As Control, v() As String) As String
        Dim count As Integer
        count = 0
        With lstCtrl
            For Each varSelected In .ItemsSelected
                If Not IsNull(varSelected) Then
                    Dim sel As String
                    sel = (lstCtrl.Column(0, varSelected))
                    strSQL = strSQL + sel & " " & v(count) & " AND "
                End If
                count = count + 1
            Next
        End With

        createSQL = strSQL
End Function

Private Sub btnBuildQuery_Click()

    If Left(strTables, 1) = "," Then
        strTables = Right(strTables, Len(strTables) - 1)
    End If

    Dim tables() As String
    tables = Split(strTables, ",")


    Dim strSQL As Variant
    strSQL = "SELECT * FROM " & strTables & " WHERE "

    For Each Table In tables

        Dim values() As String

        Select Case Table

        Case "tblPatientHistoryBaseline"
            values = Split(txtSearchValueBaseline, ",")
            strSQL = strSQL + createSQL(lstVariablesBaseline, values)
        Case "tblQuestionnaires"
            values = Split(txtSearchValueQuestionnaires, ",")
            strSQL = strSQL + createSQL(lstVariablesQuestionnaires, values)
        Case "tblTreatments"
            values = Split(txtSearchValueTreatments, ",")
           strSQL = strSQL + createSQL(lstVariablesTreatments, values)
        Case "tblFollowUpQs"
            values = Split(txtSearchValueFollowUpQs, ",")
           strSQL = strSQL + createSQL(lstVariablesFollowUpQs, values)
        End Select

    Next
        strSQL = Left(strSQL, Len(strSQL) - 5)

    Debug.Print (strSQL)
    Dim qdf As QueryDef
    Set qdf = CurrentDb.CreateQueryDef("qry" & txtQueryName, strSQL)
    DoCmd.OpenQuery qdf.Name
End Sub

以下是查询返回的内容：

LastName    FirstName    ID          Visit
Line        Georgia      1234567     0
Line        Georgia      1234567     0
Line        Georgia      1234567     0
Line        Georgia      1234567     0
Doe         Jane         0123456     0
Doe         Jane         0123456     0
Doe         Jane         0123456     0
Doe         Jane         0123456     0

以下是我生成的示例SQL：

SELECT * FROM tblQuestionnaires, tblPatientHistoryBaseline WHERE Visit = 0 AND LastName Like '*e*'

我猜测我的SQL有问题，但我无法弄清楚是什么。

谢谢！

“EDIT ----------------- LastName来自tblPatientHistoryBaseline，访问来自tblQuestionnaires

Answer 1

您没有说明tblQuestionnaires与tblPatientHistoryBaseline的关系？一个合适的JOIN可能会解决这个问题：

SELECT * 
FROM tblQuestionnaires AS q
  INNER JOIN tblPatientHistoryBaseline AS ph ON q.ID = ph.ID
WHERE Visit = 0 
  AND LastName Like '*e*'

我不太确定哪个字段来自您的选择。如果任一表中有多个记录，则上述查询仍可能产生重复。如果是这种情况，您可以将DISTINCT语句添加到查询中并指定所需的字段：

SELECT DISTINCT LastName, FirstName, ph.ID, Visit
FROM tblQuestionnaires AS q
  INNER JOIN tblPatientHistoryBaseline AS ph ON q.ID = ph.ID
WHERE Visit = 0 
  AND LastName Like '*e*'

<强> 编辑：

SELECT DISTINCT ph.ID, q.fieldname, ph.fieldname, t.fieldname, f.fieldname 
FROM tblQuestionnaires AS q
  INNER JOIN tblPatientHistoryBaseline AS ph ON q.ID = ph.ID
  INNER JOIN tblTreatments AS t ON t.ID = ph.ID
  INNER JOIN tblFollowUp AS f ON f.ID = ph.ID
WHERE Visit = 0 
  AND LastName Like '*e*'

Answer 2

在这种情况下，加入它们是强制性的。例如，应编写代码以仅指定问卷表中的匹配行。也就是说，

SELECT * 
FROM tblQuestionnaires, tblPatientHistoryBaseline 
WHERE Visit = 0 
AND LastName Like '*e*'
AND tblQuestionnaires.id = tblPatientHistoryBaseline.id

但我也建议使用更新的（过去十年）语法：

SELECT * 
FROM tblQuestionnaires q
  INNER JOIN tblPatientHistoryBaseline b
    ON q.id = b.id
WHERE q.Visit = 0 
AND b.LastName Like '*e*'

我不确定您的VISIT列或LASTNAME列的来源，但如果您使用正确的别名作为前缀，则一切都会没问题。

SQL完成的查询多次显示相同的结果（查询中同一记录的多个副本）

2 个答案: