title: Delete internal table lines where field contains the "+"?
body: <p>I want to delete entries from an internal table, which has not a "+" in one column. Now, if I want to delete it like this: </p>
  
  <pre><code>DELETE internal_table where field1 &lt;&gt; '+'.
  </code></pre>
  
  <p>it doesn't work. This means, it takes the "+" as a regex and just selects any character with length 1.</p>
  
  <p>Now I've tried several things: </p>
  
  <pre><code>DELETE internal_table where field1 &lt;&gt; '\+'.
  DELETE internal_table where field1 &lt;&gt; |\+|.
  DELETE internal_table where field1 &lt;&gt; `\+`.
  </code></pre>
  
  <p>Nothing of this works. With the String template <code>|\+|</code> I get the error "Unmasked symbol '\' in string template.  </p>
  
  <p>Field 1 is a character field with length 1. How can I escape the "+" that only the lines, which have a "+" in field1?</p>