how to find if a row was found

nephish

hey there
i am needing to find out if a row was returned in a fetch_row query.
here is the query

$Current_Hi = 'some number'

$result = mysql_query("SELECT MAX(Value) FROM `Process` WHERE Sensor_ID = 23120 ")
	$Row = mysql_fetch_row($result);
        $Recent_Hi = $Row[0] ;	
	if ($Row == FALSE) {
	$Rencent_Hi = $Current_Hi ;
	}

i am trying to set the value of $Recent_Hi to the query result, unless there are no records that match the WHERE criteria, then i want the value set to the same as $Current_Hi.

am i doing this wrong?
thanks

devinemke

[man]mysql_num_rows[/man]

nephish

cool thanks much

nephish

ok, i am using this:

$result = mysql_query("SELECT MAX(Value) FROM `Process` WHERE Sensor_ID = 23130  AND `Date_Time` > '{$CheckTime}'  ");
	$Row = mysql_fetch_row($result);
	$num_rows = mysql_num_rows($result);
	$Recent_Low = $Row[0] ;
	if ($num_rows == FALSE ){
		$Recent_Low = $Current_Low;
		}

but it doesn't seem to be working.

in fact the MAX(Value) isn't the max value at all. It isn't the lowest value, but isnt the highest either.
i think i have two problems.

the page has a reset button that becomes the $Check_Time value in the WHERE clause.
if it has been reset and there are no records available, i need it to default to the most recent value
(Represented by $Current_Low)

am i going about this wrong, still?
thanks

devinemke

$result = mysql_query("SELECT MAX(Value) FROM Process WHERE Sensor_ID = '23130' AND Date_Time > '$CheckTime'") or exit(mysql_error());
if (mysql_num_rows($result)) {$Recent_Low = mysql_result($result, 0);}
else {$Recent_Low = $Current_Low;}

nephish

ok, i am getting the same thing.
if the reset is pushed (which for the next 20-30 minutes would result in no rows being in the table) where the page is supposed to print the value for $Recent_Low, it doesn't print anything. just blank.

also, is there some weird thing about selecting with MAX ?

this is working

$result = mysql_query("SELECT MAX(`Value`) FROM `Process` WHERE `Sensor_ID` = '23120' ");
	$Row = mysql_fetch_row($result);
	$Max_Hi = $Row[0] ;

but this isn't

$result = mysql_query("SELECT MAX(`Value`) FROM `Process` WHERE `Sensor_ID` = '23130'  ");
	$Row = mysql_fetch_row($result);
	$Max_Low = $Row[0] ;

it seems to just select a record, not the MAX, or MIN, or anything that i can see would cause the record to stand out for selection, but it gets selected everytime.
but when i sort the table in knoda, it is the one listed last. so MAX is 9.74 insead of 12.33
like MAX is giving me the alphabetical hi instead of the numeric Hi .

i think , now ,, that might be the problem in all of these.

it is a text field, VARCHAR(6)
so is that what is going on?

thanks for all your help by the way.

i dont know what i am missing or if the issues have anything to do with each other

Roger_Ramjet

If it is decimal data then change the column data type to decimal. Storing numerical data in a char or varchar column is just plain stupid - for the reason you have just discovered and others.

nephish

Storing numerical data in a char or varchar column is just plain stupid .

Got it !
Its working now, thanks