title: SQL | Select (...) where 2 columns combined equal (xy)
body: <p>I have no Idea how i could solve the following problem in an effective way.</p>
  
  <p><strong>Given</strong>: </p>
  
  <p>1.
  A Telephone Number as one single String e.g.: <code>1111223344</code></p>
  
  <p>2.
  A Database with this Number <code>split in 2 different Columns</code>
  (First part of Number in <code>ColA</code>, Second Part of Number in <code>ColB</code>)
   | The Database is huge (up to 100 GB)</p>
  
  <p>Lets say in ColA is '11112'
  and in ColB is '23344' - Combined these 2 Columns are the String we are looking for. We don't know how many characters are in which column.</p>
  
  <p><strong>Need</strong>: A select Statement, that <code>combines ColA + ColB and compares it to the given String</code>. If it Equals: Select the Row.</p>
  
  <p>The selected Row/Rows will be selected and used with a .Net Application.</p>