忽略 OBDC 查询上的连接错误答案

【问题标题】：Ignore connection error on OBDC query忽略 OBDC 查询上的连接错误
【发布时间】：2017-10-26 06:08:54
【问题描述】：

我有一个查询，它连接到多台远程机器以将数据合并到一个表中。当所有机器都连接时它工作正常但偶尔任何给定的机器可能会关闭（这会导致错误），我希望我的查询忽略任何不可用的连接并继续查询的其余部分。有没有办法做到这一点？

我正在使用带有 OBDC 连接的链接表（驱动程序：MySql ODBC 5.3 Ansi 驱动程序）

这是我的查询：

SELECT "HX32" AS workcenter, "HX32." & [HX32].[dataid] AS tbldataid, HX32.dataid AS dataid, HX32.TS, DMin("[TS]","[HX32]","[TS] > #" & [TS] & "#") AS EndTS, DateDiff("s",[TS],EndTS) AS durationsec, Format(Int([durationsec]/86400)) & " " & Format([durationsec]/86400,"hh:nn:ss") AS duration, Format(TS,"mm/dd/yyyy") AS [Day], Switch(incycle=0,'Down',incycle=1,'Running') AS Status
FROM HX32
WHERE (((HX32.TS)>Date()-3) AND ((HX32.incycle)=0))

UNION ALL 

SELECT "VL65A" AS workcenter, "VL65A." & [VL65A].[dataid] AS tbldataid, VL65A.dataid AS dataid, VL65A.TS, DMin("[TS]","[VL65A]","[TS] > #" & [TS] & "#") AS EndTS, DateDiff("s",[TS],EndTS) AS durationsec, Format(Int([durationsec]/86400)) & " " & Format([durationsec]/86400,"hh:nn:ss") AS duration, Format(TS,"mm/dd/yyyy") AS [Day], Switch(incycle=0,'Down',incycle=1,'Running') AS Status
FROM VL65A
WHERE (((VL65A.TS)>Date()-3) AND ((VL65A.incycle)=0))

UNION ALL 

SELECT "VL68B" AS workcenter, "VL68B." & [VL68B].[dataid] AS tbldataid, VL68B.dataid AS dataid, VL68B.TS, DMin("[TS]","[VL68B]","[TS] > #" & [TS] & "#") AS EndTS, DateDiff("s",[TS],EndTS) AS durationsec, Format(Int([durationsec]/86400)) & " " & Format([durationsec]/86400,"hh:nn:ss") AS duration, Format(TS,"mm/dd/yyyy") AS [Day], Switch(incycle=0,'Down',incycle=1,'Running') AS Status
FROM VL68B
WHERE (((VL68B.TS)>Date()-3) AND ((VL68B.incycle)=0))
;

【问题讨论】：

这不能仅使用查询来完成。您将不得不使用一些 VBA 来测试所有机器是否都打开，然后动态生成查询 SQL。
@Erik，我希望我可以在没有 VBA 的情况下做到这一点，但如果这是唯一的选择，我认为我可以提出解决方案
好吧，查询只是 SQL，除了 Access 中的行或错误检测之外，它们没有任何逻辑。这里没有存储过程之类的东西，所以任何更复杂的事情都会失败（你可以做CREATE PROCEDURE，但这只会创建一个查询）

标签： ms-access

【解决方案1】：

我最终使用 VBA 来解决每个 @Erik 的 cmets：

它遍历每个连接检查它，如果连接良好，它会修改查询并运行。

Dim cnn As ADODB.Connection
Dim canConnect As Boolean
Set cnn = New ADODB.Connection

Dim conctns As Variant
Dim conctn As Variant

conctns = Array("HX32", "VL65A", "VL68B")

For Each conctn In conctns

    On Error GoTo sub_error

    cnn.Open conctn
    If cnn.State = adStateOpen Then
        canConnect = True

        strSQL = "SELECT '" & conctn & "' AS workcenter, '" & conctn & ".' & [" & conctn & "].[dataid] AS tbldataid, " & conctn & ".dataid AS dataid, " & conctn & ".TS, DMin('[TS]','[" & conctn & "]','[TS] > #' & [TS] & '#') AS EndTS, DateDiff('s',[TS],EndTS) AS durationsec, Format(Int([durationsec]/86400)) & ' ' & Format([durationsec]/86400,'hh:nn:ss') AS duration, Format(TS,'mm/dd/yyyy') AS [Day], Switch(incycle=0,'Down',incycle=1,'Running') AS Status FROM " & conctn & " WHERE (((" & conctn & ".TS)>Date()-3) AND ((" & conctn & ".incycle)=0));"
        CurrentDb.QueryDefs("unionall").SQL = strSQL
        DoCmd.OpenQuery "appendall", acViewNormal, acEdit
        DoCmd.OpenQuery "splithours", acViewNormal, acEdit

        MsgBox conctn & " updated: " & canConnect
        cnn.Close

    End If

sub_error:
  MsgBox conctn & ": " & Error$
  Resume sub_error_exit
sub_error_exit:
Next conctn

【讨论】：