FIREDAC QUERY 打开时老外遇到的一个问题？

http://stackoverflow.com/questions/26284351/delphi-firedac-wait-for-open-tfdquery#comment41242520_26284351

 

 

qry.Open;

ShowMessage(BoolToString(qry.Active,True);

FunctionToDoAfter(SilentMode);

明明是打开的，却显示是FALSE.

 

有人回答:

有人回答是放置了TADGUIxWaitCursor 控件。

还有人回答是否设置了异步模式，在query.ResourcOptions.ComExecMode 发现这个比较靠谱：

Edit 1

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FireDacs have four modes for commands execute. You can change it in FDQuery1.ResourceOptions.CmdExecMode. You can also set the timeout for executing command in FdQuery1.ResourceOptions.CmdExecTimeout.

The CmdExecModes are:

amBlocking （阻塞模式）-- The calling thread and GUI are blocked until an action is finished.调用query的线程和GUI被阻塞，直到一个动作完成。

amNonBlocking （非阻塞模式）-- The calling thread is blocked until an action is finished. The GUI is not blocked.调用的线程被阻塞，直到线程完成。GUI没有被阻塞。

amCancelDialog（取消对话模式） -- The calling thread and GUI are blocked until an action is finished. FireDAC shows a dialog, allowing to cancel an action.

调用query的线程和GUI被阻塞，直到一个动作完成，FireDAC 显示一个对话框，允许取消一个动作。

amAsync（异步模式） -- The calling thread and GUI are not blocked. The called method returns immediately.调用query的线程和GUI没有被阻塞，调用的方法立即返回。

You can wait while the command is executing, by checking the command state:

 

检查命令的状态：

FDQuery1.ResourceOptions.CmdExecMode := amAsync;
FDQuery1.Open;
  while FDQuery1.Command.State = csExecuting do begin
  // do something while query is executing
end;

There is 6 different command states: csInactive, csPrepared, csExecuting, csOpen, csFetching, csAborting.