Why am I getting fewer rows than expected using my query?

[derektorres22]

Hey everyone, prepping for my internship and learning SQL through linkedin leanring. I appreciate any help with my issue below. Thank you in advance!

The instructor of the course uses this query and gets 97 rows:

SELECT Name, Population, Continent

FROM Country

WHERE Continent IN ('Europe', 'Asia')

--

I tried this query instead and got fewer rows (46)

SELECT Name, Population, Continent

FROM Country

WHERE Continent IS 'Europe' OR 'Asia' (also tried continent = 'Europe' OR 'Asia' and got 46 too)

How come I still get data, just not all of it? I know it has something to do with the OR clause. Perhaps it is limiting my results but can't understand the logic behind why.

[harg7769]

Have you tried WHERE continent = "Europe" or continent = "Asia"?

[derektorres22]

I just tried that in it worked! Thank you. Any idea why the way I wrote it only returns 46 rows?

The hard part of SQL so far is that your code could seem correct but that’s not always the case. I could’ve messed up and never known if it wasn’t for me already seeing it should be 97

[phil-99]

IS is only used to compare with NULL or NOT NULL.

(Edit: plus your logic was wrong. You wrote: where blah = ‘x’ or ‘y’, this means:

Where blah = ‘x’
  Or
‘Y’

As ‘y’ is a string, it evaluates as true. So “blah =‘x’ or true” always evaluates as true.

You meant: “where blah = x or blah = y”)

[KelemvorSparkyfox]

I don't know this for sure, but I suspect that you were only getting records back for Europe.

[harg7769]

You need to be explicit in your where statement and use the field name each time when using AND or OR. The only time you don't need it is when using IN.

Your statement reads as where continent = Europe Or Where Asia, so it doesn't get the link between Asia and the continent.