Liquibase Add default value
<p>I have created a table with name person and added a column 'phone_number' using liquibase changeset. But now I want to add a default value for it. but it did not work, so far I have tried this: 
</p>

<pre><code>&lt;addDefaultValue columnName="phone_number"
                 defaultValue="+923331234567"
                 tableName="person"/&gt;
</code></pre>

<p></p>

<p>and</p>

<pre><code>&lt;changeSet author="haseeb" id="20160413123500"&gt;
    &lt;update tableName="person"&gt;
        &lt;column name="phone_number" type="varchar(255)" defaultValue="+923331234567"/&gt;
    &lt;/update&gt;
&lt;/changeSet&gt;
</code></pre>

<p>and</p>

<pre><code>&lt;changeSet author="haseeb" id="20160413123501"&gt;
    &lt;update tableName="person"&gt;
        &lt;column name="phone_number" type="varchar(255)" value="+923331234567"/&gt;
&lt;/update&gt;
</code></pre>

<p></p>

<p>Can anyone point out where I did wrong and also would adding default value  will add value to previously added rows?</p>