SQL SELECT: new column with values based on other column
<p>I have the following SQL result from a SELECT:</p>

<pre><code>col1 | col2 | col3
A    | 10   | 20
B    | 10   | 20
C    | 10   | 20
</code></pre>

<p>I want to have an additional column <code>col4</code> in the results which is filled based on the following conditions:</p>

<ul>
<li>if <code>col1</code> is <code>A</code>, then <code>col4</code> should be filled with the value from <code>col2</code></li>
<li>if <code>col1</code> is <code>B</code>, then <code>col4</code> should be filled with the value from <code>col3</code></li>
<li>if <code>col1</code> is <code>C</code>, then <code>col4</code> should be filled with the value <code>-</code></li>
</ul>

<p>The expected result therefore looks like this:</p>

<pre><code>col1 | col2 | col3 | col4
A    | 10   | 20   | 10
B    | 10   | 20   | 20
C    | 10   | 20   | -
</code></pre>