PostgreSQL: Add condition in where clause using CASE
<p>I am using PostgreSQL 8.2 and I am also new to PostgreSQL. </p>

<p>I have to add one condition in the WHERE clause depending upon specific value (49) of the field (<strong>activity.type</strong>). Here is my Query:</p>

<pre><code>SELECT activity.*
FROM activity 
LEFT JOIN event_types ON activity.customstatusid = event_types.id, getviewableemployees(3222, NULL) AS report 
WHERE 
( 
    CASE WHEN activity.type = 49 THEN 
    'activity.individualid IN(SELECT individualid from prospects where prospects.individualid = activity.individualid)' 
    ELSE 1 
    END 
)
AND activity.date BETWEEN '2016-10-01' AND '2016-10-06' 
AND activity.type IN (21, 22, 49, 50, 37, 199) 
AND (event_types.status = 1 or event_types.status IS NULL);
</code></pre>

<p>When I run above query in the command line access of PGSQL then I get below error:</p>

<pre><code>ERROR:  invalid input syntax for integer: "activity.individualid IN(SELECT individualid from prospects where prospects.individualid = activity.individualid)"
</code></pre>

<p>What I am missing here?</p>