Reporting Services - get previous column value if current is NULL
<p>I am trying to reduce the size of the data a <code>T-SQL</code> query returns to the <code>Reporting Services</code>. For example, let's say we have the following row set:</p>

<pre><code>ID  Country City
1   Germany Berlin
2   Germany Berlin
3   Germany Berlin
4   Germany Berlin
5   Germany Hamburg
6   Germany Hamburg
7   Germany Hamburg
8   Germany Hamburg
9   Germany Berlin
10  Germany Berlin
</code></pre>

<p>It can be transform easily to this:</p>

<pre><code>ID  Country City
1   Germany Berlin
2   NULL    NULL
3   NULL    NULL
4   NULL    NULL
5   NULL    Hamburg
6   NULL    NULL
7   NULL    NULL
8   NULL    NULL
9   NULL    Berlin
10  NULL    NULL
</code></pre>

<p>As I may have thousands of thousands of duplicated values (and hundreds of columns), I know that transforming the data using <code>NULLs</code> like this reduce dramatically the size of the returned data.</p>

<p>Is it possible, to implement a formula, which get's the previous row column value, if the current one is <code>NULL</code>?</p>

<p>I want to test if it will be faster to just render huge data or to work with smaller data but apply such expression.</p>