从TThread继承,写一个简单的类,用于创建操作线程返回数据库状态可以自己做一个结构,在线程内进行写操作。然后外部主线程来读取,如果有多个线程同时进行时,要创建一个List来保存结构,或者使用结构数组也行。如果使用List时子线程写状态时要进行同步控制type
TTestThread = class(TThread)
var a:string;
procedure Execute; override;
constructor Create;
destructor Destroy; override;
procedure doIt() : ;
end;constructor TTestThread.Create;
begin
inherited Create(True);
end;destructor TTestThread.Destroy;
begin
inherited Destroy;
end;
TTestThread = class(TThread)
var a:string;
procedure Execute; override;
constructor Create;
destructor Destroy; override;
procedure doIt() : ;
end;constructor TTestThread.Create;
begin
inherited Create(True);
end;destructor TTestThread.Destroy;
begin
inherited Destroy;
end;
unit TQueryThread_Unit;interfaceuses
Classes,dbtables,db,Dialogs,Sysutils,DBGrids;type
TSQLModelType = (stSelect,stExecute,stProcSelect); TQueryThread = class(TThread)
private
{ Private declarations }
FQuery : TQuery;
FSession : TSession;
FDataBase : TDataBase;
FDataSource : TDataSource;
WarningMessage :String;
procedure SetDBGrid;
procedure ShowWarning;
protected
procedure Execute; override;
public
SQLText : String;
SQLModel : TSQLModelType ;
DBGrid : TDBGrid;
constructor Create(AOwner:TComponent);
destructor Destroy;override;
end;implementationconstructor TQueryThread.Create(AOwner:TComponent);
begin
{一个Database只能让一个线程执行查询,所以要自己Create一个Session,
一个DataBase,一个Query,和一个DataSource,DataSource也是须的,
要不然在DBGrid指针的移动时候会等待直到SQL查询完毕。
如果有DataSource就不用等。线程会慢慢把数据放入DataSource,
然后在DBGrid上显示出来。}
FSession := TSession.Create(AOwner) ;
FSession.AutoSessionName := true ;
FSession.KeepConnections := true ;
FSession.Open; FDataBase := TDatabase.Create(AOwner) ;
FDataBase.SessionName := FSession.SessionName ;
FDataBase.DatabaseName := 'DB_'+FSession.SessionName ;
FDataBase.DriverName := 'MSSQL' ; {使用MS SQL Server作为后台数据库}
FDataBase.LoginPrompt := False ;
FDataBase.Params.Add('DATABASE NAME=test') ;{使用 SQL Server上的Test库}
FDataBase.Params.Add('USER NAME=sa') ;
FDataBase.Params.Add('PASSWORD=') ;
FDataBase.Params.Add('SERVER NAME=dep') ;{这里请改为自己的服务器名字} FQuery := TQuery.Create(AOwner) ;
FQuery.SessionName := FSession.SessionName ;
FQuery.DatabaseName := FDataBase.DatabaseName ; FDataSource := TDataSource.Create( AOwner );
FDataSource.DataSet := FQuery ; FreeOnTerminate := False ;
WarningMessage := '' ;
SQLModel := stSelect ;
inherited Create( True );
end;destructor TQueryThread.Destroy;
begin
FSession.Close;
//一定要先CloseFSession,然后才Free,要不然会等待直到SQL查询完毕。
FSession.Free;
FQuery.Free;
FDataBase.Free;
FDataSource.Free;
end;procedure TQueryThread.SetDBGrid;
Begin
DBGrid.DataSource := FDataSource ;
end;procedure TQueryThread.ShowWarning;
Begin
MessageDlg( WarningMessage , mtWarning , [mbOK] ,0 );
end;procedure TQueryThread.Execute;
Var
i : integer;
begin
try
if SQLText = '' then
begin
WarningMessage := '没有指定SQL查询语句.';
Synchronize( ShowWarning );
end
else if (DBGrid = nil) then
begin
WarningMessage := '没有指定DBGrid.';
Synchronize( ShowWarning );
end
else
begin
FQuery.Close;
FQuery.SQL.Text := SQLText ;
case SQLModel of
stSelect ,stProcSelect:
Begin
FQuery.Open;
Synchronize( SetDBGrid );
End;
stExecute: Begin
FQuery.ExecSQL;
End;
end;
end;
except
on E:EDBEngineError do
Begin
WarningMessage := '数据库运行出错。' + #13 + '错误代码:' ;
for i:= 0 to E.ErrorCount -1 do
WarningMessage := WarningMessage + #13+ IntToStr( E.Errors[i].ErrorCode ) +': ' + E.Errors[i].Message;
Synchronize( ShowWarning );
End
else
raise;
end;
end;end.