>>Many thanks to all who replied.
>>
>>To summarize the responses............
>>
>>When I have
>>
>>SELECT fields FROM yyy LEFT JOIN xxx ON condition
>>
>>and later have a WHERE clause involving a field in yyy
>>it essentially turns the query into an INNER JOIN
>>
>>is this right?
>
>Nope, it turns to INNER JOIN only if in WHERE you reference XXX table.
>And that is because NULLs can't be equal or different to anything even to NULLs.

Good thing I verified. I looked back and saw that my original query referenced XXX.
And your explanation makes enough sense that it might even penetrate.

THANKS again to you and all who responded.