mysql query problem

Let me explain you the whole set-up.
There are 2 tables which i need to work on for this query--- "proj_cont"
and "contact". proj_cont is a table with only 2 fields pid,cid. which is used
to associate projects with contacts. Now i want to delete all those
associations for which the notes field in contact table is blank(null).
so in effect it should delete all rows in proj_cont table whose cid =
contactid(notes=blank).
When i run this query it gives me the rows i need.
SELECT contact.contactid FROM contact WHERE contact.notes = " "

I am trying to run this query and it is giving me error 1064.
i am new to mysql so can anybody help me with this query or give me another query which will work.

$query= "SELECT contact.contactid FROM contact WHERE contact.notes = " " ";
$getvalue = mysql_query($query) or die(mysql_error());
$num_rows = mysql_num_rows($getvalue);

for($i=0; $i < $num_rows; $i++)
{
$row = mysql_fetch_array($getvalue);
DELETE * FROM proj_cont WHERE cid = "$row[i]";

}

Note that a blank field is different to a NULL field. If you want to search for NULL fields, then your query needs to look like:
"WHERE foo IS NULL"

I tried putting null, but Its still not working. Infact the echo statement gives me the number of rows correctly.
so i guess the problem is in for loop. can anybody help me with it.

$query= "SELECT contact.contactid FROM contact WHERE contact.notes = ' ' ";
$getvalue = mysql_query($query) or die(mysql_error());
$num_rows = mysql_num_rows($getvalue);
echo "$num_rows<br>"

for($i=0; $i < $num_rows; $i++)
{
$row = mysql_fetch_array($getvalue);
DELETE FROM proj_cont WHERE cid = "$row[i]";

}

is your delete statement in a variable? and then executed with mysql_query ?

as i have understood about
$row = mysql_fetch_array($getvalue);

$row[0] ---> the value of the first field/column retrieved
$row[1] ---> the value of the second field/column retrieved
....
$row[i] ----> the value of the n field/column retrieved

since your query retrieved only 1 field, when it increments 'i' (from 0 to 1)
$row[1] does not exist.

you can try to use a while loop to do the fetching

while ($row = mysql_fetch_array($getvalue))
{
$sqlDelete = "DELETE FROM proj_cont WHERE cid = '$row[0]'";
$mysql_query($sqlDelete) or die (mysql_error());
}

i may be wrong, i may be right. make things work in the test first before doing it in the real thing. good luck