An Unknown error has occurred -- EOleException 解决方法

类别:Delphi 点击:0 评论:0 推荐:
今日开发遇到一个错误:

Delphi 7.1。
使用ADO连接SQL Server,Book_ADOQuery有一个Lookup字段,每当Insert/Append的时候IDE就会弹出一个错误:

An Unknown error has occurred -- EOleException

跟踪发现错误来源于VCL LocateRecord方法的FLookupCursor.Find

function TCustomADODataSet.LocateRecord(const KeyFields: string;
  const KeyValues: OleVariant; Options: TLocateOptions;
  SyncCursor: Boolean): Boolean;

 if FieldCount = 1 then
          FLookupCursor.Find(GetFilterStr(FieldByName(KeyFields), KeyValues, Partial), 0,
             adSearchForward, EmptyParam)
   
而且如果连接Access数据库也没有问题。

通过Google发现,该Bug在Delphi 5中就有了:
http://info.borland.com/devsupport/delphi/fixes/delphi5/database.html

Area: database\ado

Reference Number: 72996
Status: Open Date Reported: 10/14/99
Severity: Commonly Encountered
Type: Minor Functionality Failure

Problem:

When using Lookup fields, inserting a record will generate "An unknown error has occured" exception in some cases.

Workaround:

Requires VCL code changes. Install Update Pack.








最后通过研究另外一个类似问题,发现:
只要把所有Lookup字段的lookupCache设为True(缺省为False)就可以避免该错误。


特记于此。


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