It doesn't return no rows, it returns row(s) with a single column set to a
NULL value. In case one of the arguments is NULL, CONCAT() will return NULL.
To replace the value of one of the fields with an empty string when it's
NULL, you can use something like: CONCAT(COAESCE(a, ''), ' ', COAESCE(b,
On 5/14/08, Afan Pasalic <afan@stripped> wrote:
> I have query
> SELECT CONCAT(r.first_name, ' ', r.last_name, '\n', r.organization, '\n',
> r.title, '\n', a.address1, '\n', a.city, ', ', a.state, ' ', a.zip, '\n',
> FROM registrants r, addresses a
> WHERE r.reg_id=121
> if any of columns has value (e.g. title) NULL, I'll get as result 0
> If query doesn't have concat() - it works fine.
> Why is that?
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