Question

Within my application, I have a set of filters that can be applied when listing resources, which builds up a query by adding WHERE clauses, etc. before executing the query. This is using SQL Server 2008.

I have two pertinent tables, one which contains some static data about the resource, and another which can contain arbitrary/optional fields pertaining to that resource.

First table is something like this (table names & fields changed):

CREATE TABLE Resources (
    ResID       varbinary(28),

    ... extra stuff omitted

    type        integer );

The second table just has name/value pairs and the corresponding resource ID

CREATE TABLE ResourceFields (
    ResID       varbinary(28) NOT NULL,

    Name        nvarchar(255) NOT NULL,
    Value       nvarchar(1024) NOT NULL);

So, for this example, there could be multiple rows in ‘ResourceFields’ with name = ‘ContactName’ for the same ResID.

What I want to do is get a count of the number of rows in the ‘Resources’ table that have more than one ‘ContactName’ listed in ‘ResourceFields’ with ‘type’ equal to some value.

I came up with this (don’t laugh — I know just enough SQL to cause problems)

SELECT count(r.ResID) 
    FROM Resources as r 
        INNER JOIN ResourceFields AS rf 
            ON rf.ResID = r.ResID 
                AND rf.name = 'ContactName' 
    WHERE r.type = 1 
    GROUP BY rf.ResID 
    HAVING COUNT(rf.Value) > 1;

but instead of returning the count of the number of rows (43 in my test set) in ‘Resources’, I get all the COUNT(rf.Value) values returned (that is, 43 individual counts).

What am I doing wrong?

Answer 1

Just use your original query as a derived table (put it in a subselect):

SELECT COUNT(*)
FROM (
    SELECT count(*) AS C
    FROM Resources as r 
        INNER JOIN ResourceFields AS rf 
            ON rf.ResID = r.ResID 
                AND rf.name = 'ContactName' 
    WHERE r.type = 1 
    GROUP BY rf.ResID 
    HAVING COUNT(rf.Value) > 1;
) s