title: SQL Server JOIN missing NULL values
body: <p>Suppose I had the following 2 tables:</p>
  <pre><code>      Table1:                                Table2:
  Col1:      Col2:     Col3:             Col1:       Col2:       Col4:
  a          b         c                 a           b           d
  e          &lt;null&gt;    f                 e           &lt;null&gt;      g
  h          i         j                 h           i           k
  l          &lt;null&gt;    m                 l           &lt;null&gt;      n
  o          &lt;null&gt;    p                 o           &lt;null&gt;      q
  </code></pre>
  <p>Now, I want to join these tables on <code>Col1</code> and <code>Col2</code> and bring back the entire set to look like:</p>
  <pre><code>     Result:
  Col1:      Col2:     Col3:     Col4:
  a          b         c         d
  e          &lt;null&gt;    f         g
  h          i         j         k
  l          &lt;null&gt;    m         n
  o          &lt;null&gt;    p         q
  </code></pre>
  <p>So, I tried a SQL like:</p>
  <pre><code>SELECT Table1.Col1, Table1.Col2, Table1.Col3, Table2.Col4
  FROM Table1
  INNER JOIN Table2
      ON Table1.Col1 = Table2.Col1 
      AND Table1.Col2 = Table2.Col2
  </code></pre>
  <p>But it isn't matching the <code>NULL</code> values in <code>Col2</code>, so I end up with:</p>
  <pre><code>     Result:
  Col1:      Col2:     Col3:     Col4:
  a          b         c         d
  h          i         j         k
  </code></pre>
  <p>How can I get the result I am looking for??</p>
  <p>Thanks!</p>