Question

我正在尝试创建一个带有过滤器的选择查询，其日期时间字段等于“无穷大”字样。和＆＃39; -infinity＆＃39;：

Here is the code.I am still getting the output as 2.3TCS3200 EVM Version.
import gnu.io.CommPort;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class JavaColorSensorDemo {

public JavaColorSensorDemo()
{
super();
}


void connect ( String portName ) throws Exception
{
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
if ( portIdentifier.isCurrentlyOwned() )
{
    System.out.println("Error: Port is currently in use");
}
else
{
    System.out.println("Connect 1/2");
    CommPort commPort = portIdentifier.open(this.getClass().getName(),9600);
if ( commPort instanceof SerialPort )
    {
        System.out.println("Connect 2/2");
        SerialPort serialPort = (SerialPort) commPort;
        System.out.println("BaudRate: " + serialPort.getBaudRate());
        System.out.println("DataBIts: " + serialPort.getDataBits());
        System.out.println("StopBits: " + serialPort.getStopBits());
        System.out.println("Parity: " + serialPort.getParity());
                     serialPort.setSerialPortParams(9600,SerialPort.DATABITS_8,SerialPort.STOPBITS_1,SerialPort.PARITY_ODD);
        serialPort.setFlowControlMode(SerialPort.FLOWCONTROL_RTSCTS_IN);
                     System.out.println("BaudRate: " + serialPort.getBaudRate());
                 System.out.println("DataBIts: " + serialPort.getDataBits());
                   System.out.println("StopBits: " + serialPort.getStopBits());
               System.out.println("Parity: " + serialPort.getParity());





        InputStream in = serialPort.getInputStream();
        OutputStream out = serialPort.getOutputStream();


        (new Thread(new SerialReader(in))).start();
        (new Thread(new SerialWriter(out))).start();
         }
      else
      {
                              System.out.println("Error: Only serial ports are handled by this example.");
   }
   }
   }
public static class SerialReader implements Runnable 
{
InputStream in;

public SerialReader ( InputStream in )
{
    this.in = in;
}

public void run ()
{
    byte[] buffer = new byte[1024];
    int len = -1;
    try
    {
        while ( ( len = this.in.read(buffer)) > -1 )
        {
            //System.out.println("Received a signal.");
            System.out.print(new String(buffer,0,len));
        }
    }
    catch ( IOException e )
    {
        e.printStackTrace();
     }            
  }
  }  
        public static class SerialWriter implements Runnable 
   {  
        OutputStream out;

      public SerialWriter ( OutputStream out )
     {
    this.out = out;
    }

       public void run ()
       {
       try
       {  

        byte[] data = {0x01,(byte)0x80,0x02,0x01};



        while ( true )
        {
           this.out.write(data);
           this.out.flush();
           Thread.sleep(1000);
                }                
        }
    catch ( IOException | InterruptedException e )
    {
        e.printStackTrace();
      }            
    }
  } 
  public static void main ( String[] args )
  {
   try
     {
    (new JavaColorSensorDemo()).connect("COM66");
     }
    catch ( Exception e )
    {
    // TODO Auto-generated catch block
       e.printStackTrace();
       }
        }
         }

我该怎么做？

Answer 1

SELECT * 
FROM mytable 
WHERE dt = 'infinity'
   OR dt = '-infinity';

这假定dt是DATE或TIMESTAMP列。

你也可以明确这一点（显然它不是一个错字）：

SELECT * 
FROM mytable 
WHERE dt = 'infinity'::timestamp
   OR dt = '-infinity'::timestamp;

Postgres：如何使用infinity和-infinity按日期时间字段进行过滤？

1 个答案: