title: How to apply a signal filter (high pass/low pass) to sql data
body: <p>My database stores time series sensor data.  I am trying to apply a high-pass/low-pass filter to clean the data before I do further processing.  how can I do that in sql?
  sample data:
  <code>
  import numpy as np
  a=(np.range(0,101))*0.1
  b=np.sin(2*np.pi*0.1*a)+np.random.random(10)-0.5
  </code>
  when ploted, the data look like the following:
  <a href="https://i.stack.imgur.com/H5h0s.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/H5h0s.png" alt="Sine function + noise "></a>
  After filtering, the data should look like this:
  <a href="https://i.stack.imgur.com/Iorah.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Iorah.png" alt="filtered data"></a></p>
  
  <p>What can I do the logics in sql?</p>