php query does not retrieve any data? - php

Question

well, i wanna pull out some data from a mysql view, but the wuery dos not seem to retrieve anything ( even though the view has data in it).
here is the code i've been "playing" with ( i'm using adodb for php)
$get_teachers=$db->Execute("select * from lecturer ");
//$array=array();
//fill array with teacher for each lesson
for($j=0;$j<$get_teachers->fetchrow();++$j){
/*$row2 = $get_lessons->fetchrow();
$row3=$row2[0];
$teach=array(array());
//array_push($teach, $row3);
$teach[$j]=mysql_fetch_array( $get_teachers, TYPE );
//echo $row3;*/
$row = $get_teachers->fetchrow();
//$name=$row[0]+" "+$row[0]+"/n";
//array_push($teach, $row1);
echo $row[0]; echo " ";echo $row[1]." ";
//$db->debug = true;
}
if i try something like "select name,surname from users", the query partially works . By partially i mean , while there are 2 users in the database, the loop only prints the last user.
the original query i wanted to execute was this
$get_teachers=$db->Execute("select surname,name from users,assigned_to,lessons
where users.UID=assigned_to.UID and lessons.LID=assigned_to.LID and
lessons.term='".$_GET['term']."'");
but because it didnt seem to do anything i tried with a view ( when you execute this in the phpmyadmin it works fine(by replacing the GET part with a number from 1 to 7 )
the tables in case you wonder are: users,assigned_to and lessons. ( assigned_to is a table connecting each user to a lesson he teaches by containing UID=userid and LID=lessonid ). What i wanted to do here is get the name+surname of the users who teach a lesson. Imagine a list tha displays each lesson+who teaches it based on the term that lesson is available.

Answer 1

Looking at http://adodb.sourceforge.net/ I can see an example on the first page on how to use the library:
$rs = $DB->Execute("select * from table where key=123");
while ($array = $rs->FetchRow()) {
print_r($array);
}
So, you should use:
while ($row = $get_teachers->fetchrow()) {
instead of:
for ($j = 0; $j < $get_teachers->fetchrow(); ++$j) {
The idea with FetchRow() is that it returns the next row in the sequence. It does not return the number of the last row, so you shouldn't use it as a condition in a for loop. You should call it every time you need the next row in the sequence, and, when there are no more rows, it will return false.
Also, take a look at the documentation for FetchRow().

Answer 2

for($j=0;$j<$get_teachers->fetchrow();++$j){
... a few lines later ...
$row = $get_teachers->fetchrow();
See how you call fetchrow() twice before actually printing anything? You remove two rows from the result set for every 1 you actually use.
while ($row = $get_teachers->fetchrow()) {
instead and don't call fetchrow() again within the loop.

Answer 3

Because you're fetching twice first in the loop
for($j=0;$j<$get_teachers->fetchrow();++$j){
... some code ...
// And here you fetch again
$row = $get_teachers->fetchrow();
You should use it like this
while ($row = $get_teachers->fetchrow()) {