title: How to remove unknown characters using T-SQL?
body: <p>I try to do a script to eliminate the Chinese characters in a string and between the Chinese characters I want to remove. Please see the example below. Thank you.</p>
  
  <pre><code>select LTRIM(SUBSTRING('Tower 6A 第6A座', PATINDEX('%[a-zA-Z0-9]%', 'Tower 6A 第6A座'), LEN('Tower 6A 第6A座')))
  select LTRIM(REPLACE(SUBSTRING('Tower 6A 第6A座', CHARINDEX(N'樓', 'Tower 6A 第6A座') + 1, LEN('Tower 6A 第6A座')), ' ', ''))
  </code></pre>
  
  <p>Sample string:</p>
  
  <pre><code>Tower 6A 第6A座
  Tower 3 第3座
  </code></pre>
  
  <p>Bad Result:</p>
  
  <pre><code>Tower 6A ?6A?
  Tower6A?6A?
  Tower 3 ?3?
  Tower3?3?
  </code></pre>
  
  <p>Good result, I want to achieve:</p>
  
  <pre><code>Tower 6A
  Tower 6A
  Tower 3
  Tower 3
  </code></pre>