==============unit2:线程thread1;==================== unit Unit2; interface uses Classes {$IFDEF MSWINDOWS} ,mplayer, Windows {$ENDIF};implementation uses unit1;procedure thread1.Execute; var m:TmediaPlayer; begin SetName; Unit1.Form1.MediaPlayer1.Open; unit1.Form1.MediaPlayer1.Play; { Place thread code here } end;end. ==========Unit1:mainform=============Form1中放一mediaplayer; FileName:=C:\WINDOWS\MEDIA\The Microsoft Sound.wav deviceType:=dtAutoSelectuses unit2; procedure TForm1.Button5Click(Sender: TObject); var m:Thread1; begin m:=Thread1.Create(false); end;
select * from t1 union select * from t2
select * from t1 union select * from t2 用一个query就可以了
select * from t1 union select * from t2
虽然可以合并查询结果,但是无法多线程同时查询了
求可实现多线程查询同时合并查询结果集的方法
select * from t1
union
select * from t2
吧
因为数据量比较大
select * from t1
union
select * from t2
union
select * from t3
.....
这样下去查询速度会很慢的阿
各个query的插到一个与dbgrid连接的query中,当然,每插一个的同时你都得判断一下与已有的是否重复...
这样比union应该是慢很多了,不信可以一试...
首先假设
表a:字段 :id,name,^
表b: 字段: id,name,^
select a.id,a.name,b.id,b.name from a,b where ^^^^^
1.我现在想从来张表中取数据,但是在dbgrid中重新定义了tcolumn 的title,color等
这样在程序运行期间我就必须重新指定:dbgrid 中各列 fieldname 属性可是我 指定了,编译通过,可是运行的时候错误,没有任何数据显示,请问 各位:我应该怎么来指定fieldname 呢?
谢谢
unit Unit2;
interface
uses
Classes {$IFDEF MSWINDOWS} ,mplayer, Windows {$ENDIF};implementation
uses unit1;procedure thread1.Execute;
var
m:TmediaPlayer;
begin
SetName;
Unit1.Form1.MediaPlayer1.Open;
unit1.Form1.MediaPlayer1.Play;
{ Place thread code here }
end;end.
==========Unit1:mainform=============Form1中放一mediaplayer;
FileName:=C:\WINDOWS\MEDIA\The Microsoft Sound.wav
deviceType:=dtAutoSelectuses unit2;
procedure TForm1.Button5Click(Sender: TObject);
var
m:Thread1;
begin
m:=Thread1.Create(false);
end;
union
select * from t2
用一个query就可以了