Re: LEFT joins

In general, you should not worry about faster query sintax, since mysql should (but i'm not sure) have an "optimizer" inside wich translate your sintax query in a "better" efficient one. Anyway, the "where" statement is perfectly equal to the "join" operator, it is called, in general, "theta-join" and in this case it is called "equi-join" (equi...because in the where statement you only compare attributes by the '=' operator). The only reason you want to use the "left-join", which is a particular case for a general "outer-join", is if you want to fill your result with "NULL" values rather than an empty records. Jochem Maas ha scritto:

OR.... SELECT b.fldName,

        b.fldEmail,
        b.fldCountryCode,
        d.fldCode as FCode,
        b.fldMobile,
        a.fldTime as Time,
        c.fldUsername as Username

FROM tblSubscribersChoices a LEFT JOIN tblUser c ON c.fldClientID = a.fldChoice LEFT JOIN tblSubscribers b ON b.fldID = a.fldClientID LEFT JOIN tc_countries d ON d.fldCode = b.fldCountryCode ORDER BY Username ASC

and if that works but doesn't give you repeat records try adding the DISTINCT keyword after SELECT. <snip>

Why are you so intrested in LEFT JOIN? I cn't help much since i don't

I'm not but his original query used JIONs and a LEFT JOIN is (IMHO) the easiest to understand. I didn't have the presence of mind to rewrite the query using a simple WHERE clause - hope your tip helps him. btw: can anyone say if the LEFT JOIN or the alternative WHERE statement (in general?) is faster?

know the schema of the db and i can't see clear the meaning of the tables in the query. Anyway try this: <SQL> SELECT b.fldName,

         b.fldEmail,
         b.fldCountryCode,
         d.fldCode as FCode,
         b.fldMobile,
         a.fldTime as Time,
         c.fldUsername as Username

FROM tblSubscribersChoices a, tblUser c, tblSubscribers b,

    tc_countries d

WHERE c.fldClientID = a.fldChoice AND b.fldID = a.fldClientID AND

    d.fldCode = b.fldCountryCode

ORDER BY Username ASC </SQL> Bye