在建立数据连接中SQLConnection1的属性中ConnectionName 填入连接名称(数据库是绝对路径),但在发布程序时,想改变数据存放的位置,在数据模块中写下列代码: 
procedure TDM.DataModuleCreate(Sender: TObject);
begin
SQLConnection1.Connected:=false;
SQLConnection1.Params.Clear;
SQLConnection1.Params.Values['user_name']:='sysdba';
SQLConnection1.Params.values['password']:='masterkey';
sqlConnection1.Params.Values['SQLDialect']:='3';
SQLConnection1.Params.Values['database']:=extractfilepath(paramstr(0)) 'DATA\test.ib';
SQLConnection1.Connected:=true;

end;
在程序运行中,提示找不到数据库的路径.
appName :xmain.exe appver:0.0.0.0 modname:kernel32.dll
modver:5.1.2600.2945 offset:00012a5b

问题已解决
将下列语句写在SQLConnection1的beforConnection事件中

SQLConnection1.Params.Clear;
SQLConnection1.Params.Values['user_name']:='sysdba';
SQLConnection1.Params.values['password']:='masterkey';
sqlConnection1.Params.Values['SQLDialect']:='3';
SQLConnection1.Params.Values['database']:=extractfilepath(paramstr(0)) 'DATA\test.ib';