SQL Too few parameters when using WHERE clause and GROUP BY - sql

Question

I'm trying to write a query that will display a list of actors who star in at least 1 movie. I'm getting a "Too few parameters. Expected 2." error when I put the WHERE clause in. How do I fix this?
<cfquery name="qry1" datasource="torture">
SELECT
Actors.ActorID,
Actors.First_Name + ' ' + Actors.Last_Name AS Fullname,
COUNT( Title ) AS Titles
FROM
Actors
RIGHT JOIN Videos ON Actors.ActorID = Videos.ActorID
WHERE
Fullname <> NULL AND
Titles > 0
GROUP BY
Actors.ActorID,
Actors.First_name,
Actors.Last_Name;
</cfquery>
<cfform name="form" action="Page7Receiver.cfm">
<cfselect name="actor"
query="qry1"
value="ActorID"
display="FullName"
required="Yes"
multiple="No"
size="8">
</cfselect>
<br><input type="Submit" value="Submit">
</cfform>

Answer 1

The problem is caused by referencing names in your WHERE query that don't exist yet (Fullname and Titles).
Despite that SQL is in SELECT... FROM... WHERE... GROUP BY... HAVING... ORDER BY... order, in reality the SELECT is evaluated at the end, so your Fullname and Titles columns are not yet available in your WHERE clause.
I suggest reformulating the query like so:
SELECT
Actors.ActorId,
Actors.First_Name + ' ' + Actors.Last_Name AS FullName,
COALESCE( VideoInfo.VideoCount, 0 ) AS Titles
FROM
Actors
LEFT OUTER JOIN
(
SELECT
ActorId,
COUNT( * ) AS VideoCount
FROM
Videos
GROUP BY
ActorId
) AS VideoInfo ON Actors.ActorId = VideoInfo.ActorId
WHERE
COALESCE( VideoInfo.VideoCount, 0 ) > 0
AND
Actors.First_Name IS NOT NULL
AND
Actors.Last_Name IS NOT NULL
If we change it to an INNER JOIN then we can skip the Titles > 0 check because the nature of INNER JOIN means if an Actor has no Videos then there won't be a table-join on that ActorId anyway.
SELECT
Actors.ActorId,
Actors.First_Name + ' ' + Actors.Last_Name AS FullName,
VideoInfo.VideoCount AS Titles
FROM
Actors
INNER JOIN
(
SELECT
ActorId,
COUNT( * ) AS VideoCount
FROM
Videos
GROUP BY
ActorId
) AS VideoInfo ON Actors.ActorId = VideoInfo.ActorId
WHERE
Actors.First_Name IS NOT NULL
AND
Actors.Last_Name IS NOT NULL
Note, the <> NULL is not valid SQL. NULL is special: you have to use IS NOT NULL or IS NULL instead.