I've found that FileMaker is very particular in its formatting of queries using the ExecuteSQL function. In many cases, standard SQL syntax will work fine, but in some cases you have to make some slight (but important) tweaks.
I can see two things here that might be causing the problem...
ExecuteSQL ("
SELECT M::MovieName FROM Movies M INNER JOIN Genres G ON
M::GenreId=G::GenreId
WHERE M::Rating =
(SELECT MAX(M2::Rating) FROM Movies M2 WHERE M2::GenreId = M::GenreId)
"; "" ; "")
- You can't use the standard FMP
table::field
format inside the query.
Within the quotes inside the ExecuteSQL function, you should follow the SQL format oftable.column
. SoM::MovieName
should beM.MovieName
. - I don't see an
AS
anywhere in your code.
In order to create an alias, you must state it explicitly. For example, in yourFROM
, it should beMovies AS M
.
I think if you fix those two things, it should probably work. However, I've had some trouble with JOINs myself, as my primary experience is with FMP, and I'm only just now becoming more familiar with SQL syntax.
Because it's incredibly hard to debug SQL in FMP, the best advice I can give you here is to start small. Begin with a very basic query, and once you're sure that's working, gradually add more complicated elements one at a time until you encounter the dreaded ?
.
There's a number of great posts on FileMaker Hacks all about ExecuteSQL:
Since you're already familiar with SQL, I'd start with this one: The Missing FM 12 ExecuteSQL Reference. There's a link to a PDF of the entire article if you scroll down to the bottom of the post.
I was going to recommend a few more specific articles (like the series on Robust Coding, or Dynamic Parameters), but since I'm new here and I can't include more than 2 links, just go to FileMaker Hacks and search for "ExecuteSQL". You'll find a number of useful posts.
NB If you're using FMP Advanced, the Data Viewer is a great tool for testing SQL. But beware: complex queries on large databases can sometimes send it into fits and freeze the program.