[英]Excel VBA QueryTable Parameter Fails with Null Value
是否可以将NULL
值传递给QueryTable.Parameters
以在 (My)SQL 查询中使用?
从另一个答案中,我们可以看到使用ADODB.Command
可以做到这一点,但不幸的是, ADODB
在 Excel for Mac 中不可用,我正在开发的应用程序应该可以在 Windows 和 Mac 上运行。
下面的内容被确认为 Windows 错误(我假设是 Mac)。
如果您将param_value
设置为 Null 以外的任何值,以下 VBA 代码可以正常工作,但是一旦您尝试使用 Null,它就会失败。
Option Explicit
Sub Test()
' SQL '
Dim sql As String
sql = "SELECT ? AS `something`"
Dim param_value As Variant
'param_value = "hello" ' this works
'param_value = Null ' this does NOT work
' QUERY & TABLE CONFIG '
Dim my_dsn As String
Dim sheet_name As String
Dim sheet_range As Range
Dim table_name As String
my_dsn = "ODBC;DSN=my_dsn;"
sheet_name = "Sheet1"
Set sheet_range = Range("$A$1")
table_name = "test_table"
' EXECUTE QUERY '
Dim qt As QueryTable
Set qt = ActiveWorkbook.Worksheets(sheet_name).ListObjects.Add( _
SourceType:=xlSrcExternal, _
Source:=my_dsn, _
Destination:=sheet_range _
).QueryTable
With qt
.ListObject.Name = table_name
.ListObject.DisplayName = table_name
.RowNumbers = False
.FillAdjacentFormulas = False
.PreserveFormatting = True
.RefreshOnFileOpen = False
.BackgroundQuery = False
.RefreshStyle = xlInsertDeleteCells
.SavePassword = False
.SaveData = True
.AdjustColumnWidth = True
.RefreshPeriod = 0
.PreserveColumnInfo = False
.CommandText = sql
End With
Dim param As Parameter
Set param = qt.Parameters.Add( _
"param for something", _
xlParamTypeUnknown _
)
param.SetParam xlConstant, param_value
qt.Refresh BackgroundQuery:=False
End Sub
将param_value
设置为 "hello" 时,成功的结果如下所示:
(带有命令提示符屏幕截图的底部是 MySQL 日志记录的内容)。
这是将param_value
设置为 Null 时的错误:
您可以从 MySQL 日志中看到,成功的查询首先执行Prepare
,然后Execute
查询。
而失败的 Null 查询执行Prepare
,但从未Execute
。
在线搜索run-time error -2147417848 (80010108)
无济于事; 人们报告说,从“冻结窗格”问题到“用户表单”问题的所有问题都得到了这一点,而我没有看到与QueryTable
相关的任何内容。
VBA 代码不仅无法按预期工作,还会以某种方式破坏工作簿:
(在查询失败后尝试保存文件时会发生这种情况;关闭而不保存,您可以重新打开)。
MySQL 日志显示 VBA 连接失败Quit
以及 Excel 文件损坏的事实使我认为不仅不可能在QueryTable.Parameters
使用 Null ,而且它也是底层软件。
我是否遗漏了什么,或者不可能将空参数传递给 QueryTable?
作为对投票结果的回应:我的观点是应该有一种方法可以将参数作为NULL
传递,就像这里引用的一样。
由于 Null 的这个问题,以及xlParamTypeDate没有从十进制转换为“yyyy-mm-dd”,我最终滚动了我自己的参数化类模块。 它已发布在下面作为对这个问题的回答。
如果有人知道如何使用QueryTable.Parameters
完成此操作,请发帖,我将选择您的答案。 但以下是自定义解决方案。
对于除所有char
之外的SqlTypes
,参数化都是自定义的,但由于尝试实现它时可能发生的各种转义极端情况, 。char
仍然使用QueryTable.Parameters
编辑到上面的删除线:我实际上已经恢复为使用此自定义参数化手动处理字符参数。 我忘记了遇到的确切极端情况,但得出的最终结论是,对于具有特定查询字符串的特定字符参数的奇异情况,VBA 参数化失败了......我完全不知道故障点在哪里是在 Microsoft 的 VBA 方法的黑匣子中生成的,但我验证了一个事实确定性,即对于这个看似随机的情况,字符串参数根本没有传递给 (My)SQL 引擎。 我只想说,我的经验是,在QueryTable.Parameters
方法根本无法在所有信任。 我的建议是取消注释GetValueAsSqlString = Replace$(Replace$(Replace$(CStr(value), "\\", "\\\\"), "'", "\\'"), """", "\\""")
并删除SetQueryTableSqlAndParams
中的IF char THEN
逻辑。 由于不同的引擎有不同的字面量,我把它留作练习,让读者在他们的情况下处理; 例如,上面的Replace$()
代码可能(也可能不)具有您希望使用包含\\n
的 VBA 字符串看到的行为。
我注意到 QueryTable 的一个不一致之处是,如果您执行SELECT "hello\\r\\nthere" AS s
的非参数化查询,查询将返回换行符(如预期),但如果您使用 QueryTable.Parameters xlParamTypeChar
和"hello\\r\\nthere"
,然后它将返回原始反斜杠。 因此在参数化字符串文字时必须使用vbCrLf
等。
SqlParams
类模块:
Option Explicit
' https://web.archive.org/web/20180304004843/http://analystcave.com:80/vba-enum-using-enumerations-in-vba/#Enumerating_a_VBA_Enum '
Public Enum SqlTypes
[_First]
bool
char
num_integer
num_fractional
dt_date
dt_time
dt_datetime
[_Last]
End Enum
Private substitute_string As String
Private Const priv_sql_type_index As Integer = 0
Private Const priv_sql_val_index As Integer = 1
Private params As New collection
Private Sub Class_Initialize()
substitute_string = "?"
End Sub
Public Property Get SubstituteString() As String
' This is the string to place in the query '
' i.e. "SELECT * FROM users WHERE id = ?" '
SubstituteString = substitute_string
End Property
Public Property Let SubstituteString(ByVal s As String)
substitute_string = s
End Property
Public Sub SetQueryTableSqlAndParams( _
ByVal qt As QueryTable, _
ByVal sql As String _
)
Dim str_split As Variant
str_split = Split(sql, substitute_string)
Call Assert( _
(GetArrayLength(str_split) - 1) = params.Count, _
"Found " & (GetArrayLength(str_split) - 1) & ", but expected to find " & params.Count & " of '" & substitute_string & "' in '" & sql & "'" _
)
qt.Parameters.Delete
sql = str_split(0)
Dim param_n As Integer
For param_n = 1 To params.Count
If (GetSqlType(param_n) = SqlTypes.char) And Not IsNull(GetValue(param_n)) Then
sql = sql & "?"
With qt.Parameters.Add( _
param_n, _
xlParamTypeChar _
)
.SetParam xlConstant, GetValue(param_n)
End With
Else
sql = sql & GetValueAsSqlString(param_n)
End If
sql = sql & str_split(param_n)
Next param_n
qt.CommandText = sql
End Sub
Public Property Get Count() As Integer
Count = params.Count
End Property
Public Sub Add( _
ByVal sql_type As SqlTypes, _
ByVal value As Variant _
)
Dim val_array(1)
val_array(priv_sql_type_index) = sql_type
Call SetThisToThat(val_array(priv_sql_val_index), value)
params.Add val_array
End Sub
Public Function GetSqlType(ByVal index_n As Integer) As SqlTypes
GetSqlType = params.Item(index_n)(priv_sql_type_index)
End Function
Public Function GetValue(ByVal index_n As Integer) As Variant
Call SetThisToThat( _
GetValue, _
params.Item(index_n)(priv_sql_val_index) _
)
End Function
Public Sub Update( _
ByVal index_n As Integer, _
ByVal sql_type As SqlTypes, _
ByVal value As Variant _
)
Call SetSqlType(index_n, sql_type)
Call SetValue(index_n, value)
End Sub
Public Sub SetSqlType( _
ByVal index_n As Integer, _
ByVal sql_type As SqlTypes _
)
params.Item(index_n)(priv_sql_type_index) = sql_type
End Sub
Public Sub SetValue( _
ByVal index_n As Integer, _
ByVal value As Variant _
)
Call SetThisToThat( _
params.Item(index_n)(priv_sql_val_index), _
value _
)
End Sub
Public Function GetValueAsSqlString(index_n As Integer) As String
Dim value As Variant
Call SetThisToThat(value, GetValue(index_n))
If IsNull(value) Then
GetValueAsSqlString = "NULL"
Else
Dim sql_type As SqlTypes
sql_type = GetSqlType(index_n)
Select Case sql_type
Case SqlTypes.num_integer
GetValueAsSqlString = CStr(value)
Call Assert( _
StringIsInteger(GetValueAsSqlString), _
"Expected integer, but found " & GetValueAsSqlString, _
"GetValueAsSqlString" _
)
Case SqlTypes.num_fractional
GetValueAsSqlString = CStr(value)
Call Assert( _
StringIsFractional(GetValueAsSqlString), _
"Expected fractional, but found " & GetValueAsSqlString, _
"GetValueAsSqlString" _
)
Case SqlTypes.bool
If (value = True) Or (value = 1) Then
GetValueAsSqlString = "1"
ElseIf (value = False) Or (value = 0) Then
GetValueAsSqlString = "0"
Else
err.Raise 5, "GetValueAsSqlString", _
"Expected bool of True/False or 1/0, but found " & value
End If
Case Else
' Everything below will be wrapped in quotes as a string for SQL '
Select Case sql_type
Case SqlTypes.char
err.Raise 5, "GetValueAsSqlString", _
"Use 'QueryTable.Parameters.Add' for chars"
' GetValueAsSqlString = Replace$(Replace$(Replace$(CStr(value), "\", "\\"), "'", "\'"), """", "\""") ''
Case SqlTypes.dt_date
If VarType(value) = vbString Then
GetValueAsSqlString = value
Else
GetValueAsSqlString = Format(value, "yyyy-MM-dd")
End If
Call Assert( _
StringIsSqlDate(GetValueAsSqlString), _
"Expected date as yyyy-mm-dd , but found " & GetValueAsSqlString, _
"GetValueAsSqlString" _
)
Case SqlTypes.dt_datetime
If VarType(value) = vbString Then
GetValueAsSqlString = value
Else
GetValueAsSqlString = Format(value, "yyyy-MM-dd hh:mm:ss")
End If
Call Assert( _
StringIsSqlDatetime(GetValueAsSqlString), _
"Expected datetime as yyyy-mm-dd hh:mm:ss, but found " & GetValueAsSqlString, _
"GetValueAsSqlString" _
)
Case SqlTypes.dt_time
If VarType(value) = vbString Then
GetValueAsSqlString = value
Else
GetValueAsSqlString = Format(value, "hh:mm:ss")
End If
Call Assert( _
StringIsSqlTime(GetValueAsSqlString), _
"Expected time as hh:mm:ss, but found " & GetValueAsSqlString, _
"GetValueAsSqlString" _
)
Case Else
err.Raise 5, "GetValueAsSqlString", _
"SqlType of " & GetSqlType(index_n) & " has not been configured for escaping"
End Select
GetValueAsSqlString = "'" & GetValueAsSqlString & "'"
End Select
End If
End Function
依赖模块:
Function GetArrayLength(ByVal a As Variant) As Integer
' https://stackoverflow.com/a/30574874 '
GetArrayLength = UBound(a) - LBound(a) + 1
End Function
Sub Assert( _
ByVal b As Boolean, _
ByVal msg As String, _
Optional ByVal src As String = "Assert" _
)
If Not b Then
err.Raise 5, src, msg
End If
End Sub
Sub SetThisToThat(ByRef this As Variant, ByVal that As Variant)
' Used if "that" can be an object or a primitive '
If IsObject(that) Then
Set this = that
Else
this = that
End If
End Sub
Function StringIsDigits(ByVal s As String) As Boolean
StringIsDigits = Len(s) And (s Like String(Len(s), "#"))
End Function
Function StringIsInteger(ByVal s As String) As Boolean
If Left$(s, 1) = "-" Then
StringIsInteger = StringIsDigits(Mid$(s, 2))
Else
StringIsInteger = StringIsDigits(s)
End If
End Function
Function StringIsFractional( _
ByVal s As String, _
Optional ByVal require_decimal As Boolean = False _
) As Boolean
' require_decimal means that the string must contain a "." decimal point '
Dim n As Integer
n = InStr(s, ".")
If n Then
StringIsFractional = StringIsInteger(Left$(s, n - 1)) And StringIsDigits(Mid$(s, n + 1))
ElseIf require_decimal Then
StringIsFractional = False
Else
StringIsFractional = StringIsInteger(s)
End If
End Function
Function StringIsDate(ByVal s As String) As Boolean
StringIsDate = True
On Error GoTo no
IsObject (DateValue(s))
Exit Function
no:
StringIsDate = False
End Function
Function StringIsSqlDate(ByVal s As String) As Boolean
StringIsSqlDate = StringIsDate(s) And ( _
(s Like "####-##-##") _
Or (s Like "####-#-##") _
Or (s Like "####-##-#") _
Or (s Like "####-#-#") _
)
End Function
Function StringIsTime(ByVal s As String) As Boolean
StringIsTime = True
On Error GoTo no
IsObject (TimeValue(s))
Exit Function
no:
StringIsTime = False
End Function
Function StringIsSqlTime(ByVal s As String) As Boolean
StringIsSqlTime = StringIsTime(s) And ( _
(s Like "##:##:##") _
Or (s Like "#:##:##") _
)
End Function
Function StringIsDatetime(ByVal s As String) As Boolean
Dim n As Integer
n = InStr(s, " ")
If n Then
StringIsDatetime = StringIsDate(Left$(s, n - 1)) And StringIsTime(Mid$(s, n + 1))
Else
StringIsDatetime = False
End If
End Function
Function StringIsSqlDatetime(ByVal s As String) As Boolean
Dim n As Integer
n = InStr(s, " ")
If n Then
StringIsSqlDatetime = StringIsSqlDate(Left$(s, n - 1)) And StringIsSqlTime(Mid$(s, n + 1))
Else
StringIsSqlDatetime = False
End If
End Function
示例用法:
Dim params As SqlParams
Set params = New SqlParams
params.Add SqlTypes.num_integer, 123
Dim sql As String
sql = "SELECT * FROM users WHERE id = " & params.SubstituteString
Dim odbc_str As String
odbc_str = "ODBC;DSN=my_dsn;"
Dim sheet As Worksheet
Set sheet = ThisWorkbook.Worksheets("Sheet1")
Dim table_name As String
table_name = "test_table"
Dim qt As QueryTable
Set qt = sheet.ListObjects.Add( _
SourceType:=xlSrcExternal, _
Source:=odbc_str, _
Destination:=Range("$A$1") _
).QueryTable
With qt
.ListObject.name = table_name
.ListObject.DisplayName = table_name
.RowNumbers = False
.FillAdjacentFormulas = False
.PreserveFormatting = True
.RefreshOnFileOpen = False
.BackgroundQuery = False
.RefreshStyle = xlInsertDeleteCells
.SavePassword = False
.SaveData = True
.AdjustColumnWidth = True
.RefreshPeriod = 0
.PreserveColumnInfo = False
End With
Call params.SetQueryTableSqlAndParams(qt, sql)
qt.Refresh BackgroundQuery:=False
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