PHP/MySQL: using MIN() on an empty set of rows -> query error

[Jim Hatfield]

I'm using: "select min(objid) from table_name where objid > $objid"
to select the next row in a sequence where there may be gaps. It
works fine unless the where clause results in an empty set.

From the command line, a value is *always* returned, which is NULL
when the set of rows selected by the where clause is empty. I wasn't
sure what I expected mysql_query to return. I didn't expect a FALSE
result, since the query is syntactically valid, but that's what I got.

Surely this is a bug? An empty result set would seem to be the correct
response, not a query error.

jim
--
Jim Hatfield

[Jim Hatfield]

On Tue, 31 Aug 2004 16:22:26 +0100, Jim Hatfield <ji**********@insignia.com> wrote:

Surely this is a bug? An empty result set would seem to be the correct
response, not a query error.

Or even one row with an empty string as the returned value, which
is what I got after I played around with it for a while. I must have
been doing something else wrong...
--
Jim Hatfield

[Michael Fesser]

.oO(Jim Hatfield)

I'm using: "select min(objid) from table_name where objid > $objid"
to select the next row in a sequence where there may be gaps. It
works fine unless the where clause results in an empty set.

From the command line, a value is *always* returned, which is NULL
when the set of rows selected by the where clause is empty. I wasn't
sure what I expected mysql_query to return.
A resource ID.
I didn't expect a FALSE
result, since the query is syntactically valid, but that's what I got.
A return value FALSE indicates an error. Check mysql_error().

mysql_query() always returns a resource ID if the query was successful,
even if the result set is empty or contains NULL. What versions of PHP
and MySQL do you use?
Surely this is a bug? An empty result set would seem to be the correct
response, not a query error.

In this case a result set with one value NULL would be correct (there's
no min-value in an empty set).

Micha