Empty set

[AL123]

I am new.

I am trying to output a list of urls in a small app I am working on.

Here is my first sql query that is printing the links:

"SELECT categoryId FROM categories";

 

When you click on the link a second table is populated with the business information.

 

SELECT * FROM business, businessCat WHERE businessCat.categoryId = '$catId' AND business.businessId = 'businessCat.categoryId'

So when you click on the link the script calls itself, showing the business info.

In trying to debug the problem in phpMyAdmin, I subsituted $catId for a value from the DB - 'Automotive'.

No matter what, I return an empty set, here is the error:  MySQL returned an empty result set (i.e. zero rows). ( Query took 0.0005 sec )

any suggestions??

 

AL.

 

[Maq]

I subsituted $catId for a value from the DB - 'Automotive'.

No matter what, I return an empty set, here is the error:  MySQL returned an empty result set (i.e. zero rows). ( Query took 0.0005 sec )

That's not an error.  If you're sure that 'Automotive' exists as a categoryId in the businessCat table, then your join is wrong.

[AL123]

Thanks I will give that a try.

 

AL

[AL123]

Yes Automotive is there

 

AL

[DavidAM]

I suspect your query is not correct.

SELECT * FROM business, businessCat 
WHERE businessCat.categoryId = '$catId' 
AND business.businessId = 'businessCat.categoryId'

 

It looks like you are joining the categoryId (from businessCat) to the businessId (in business) (and what are those quotes doing in there?). Shouldn't that be something like this:

SELECT * FROM business, businessCat 
WHERE businessCat.categoryId = '$catId' 
AND business.businessId = businessCat.businessId

(changes in the last line)

 

or, using the JOIN phrase:

SELECT * 
FROM business JOIN businessCat ON business.businessId = businessCat.businessId
WHERE businessCat.categoryId = '$catId' 

 

If categoryId is a number, then your page should be passing that number, not the name like "Automotive".

I'm just guessing here since we don't have the table layouts, but I think this should help. If it doesn't, then post your table layouts (Table name, column names and datatypes) and possibly some sample data, so we can figure it out.

[AL123]

Thanks guys. I have to leave, but I will try to pick this up later this evening (with the table info).

 

AL.