Script isn't working

claire

Hi, any ideas of why this script isn't working?
I'm comparing names in two databases.
For each name found in the first database a comparison is made while searching the second database. If a match is found a flag is set to 1. If no match the flag is 0, and the name should be deleted.
The searching of names are OK, I've echoed out the names. It seems to be the flag that doesn't work!

Searching names in the first database

$result=mysql_query("SELECT * FROM tbl WHERE M='$m' ");

$i=1;

 WHILE ($a = mysql_fetch_array($result))   {

$member[$i] = $a['name'];

$i++;

$no = count ($member);

Searching names in the second database and comparing them with each found name in the first search

$result = mysql_query (SELECT * FROM tbl WHERE T = $t ");

 WHILE ($b = mysql_fetch_array($result))  {

$user = $b['name'];
$flag == 0;

										  for ($i=1; $i<=$no; $i++)  {

if ($user == $member[$i] ) $flag == 1;

}

if ($flag == 0) {

$sql = mysql_query ("DELETE FROM tbl WHERE Name = '$user' ")

}

Anon

The double '==' is a comparison so your not setting $flag.

$flag == 0;
//should be $flag=0;
for ($i=1; $i<=$no; $i++) {
if ($user == $member[$i] ) $flag == 1;
// if ($user == $member[$i] ) $flag = 1;
}

Try changing your code and let us know if it works 😉

claire

Thanks Martin,

I changed the $flag== to $flag= but it still isn't working....

It doesn't delete a user name which that should be deleted since that name isn't in the memberlist.

Any other ideas???

I've been banging my head black and blue over this....so I really appreciate every help I can get!

Anon

I'm not at home so I can't test this but give it a go.

$result=mysql_query("SELECT * FROM tbl WHERE M='$m' ");

WHILE ($a = mysql_fetch_array($result)) {

$member[] = $a['name'];

}

$result2 = mysql_query (SELECT * FROM tbl WHERE T = $t ");

WHILE ($b = mysql_fetch_array($result2)) {

$user = $b['name'];

for ($i=0; $i<=count($member); $i++) {

if ($user == $member[$i] ){
mysql_query ("DELETE FROM tbl WHERE Name = '$user'")
}

}

claire

That what I had to start with! (it should be $user not equal to $member! - then delete)
The problem with running the DELETE directly (without setting a flag) is that $user is compared to the first member name [1]. If they are not the same the username is deleted. However it may well be the same as member name [2] and thus should not be deleted!

/claire

Anon

Sorry Claire,
I don't seem to be helping here (I'm a bit dense). Could you perhaps brake it down into steps for me.

claire

Hi again!

(using your notation which is neater) this is what I want the script to do

//search the member database for all names

                   $result=mysql_query("SELECT * FROM tbl WHERE M='$m' "); 



                   WHILE ($a = mysql_fetch_array($result)) { 

                   $member[] = $a['name']; 

                   }

//search the user database for all names

                   $result2 = mysql_query (SELECT * FROM tbl WHERE T = $t "); 

                   WHILE ($b = mysql_fetch_array($result2)) { 


                   $user = $b['name'];

$flag = 0;
//take the first username found in the WHILE loop and enter the FOR loop. Let the FOR loop check that first username against all the member names. If a match is found set the flag to 1 (and exit).

                   for ($i=0; $i<=count($member); $i++) { 

                   if ($user == $member[$i] ) $flag= 1;

// If the flag is still set to 0, no matching name was found and the username should be deleted.
if $flag=0 {
mysql_query ("DELETE FROM tbl WHERE Name = '$user'")
}

                   } 

                   }

hm... as I look at it now I see a difference in our notations re the ending } . Could it be that I finish any of my loops to early?

Anon

Please copy/paste all the code below and try:

//search the member database for all names

$result=mysql_query("SELECT * FROM tbl WHERE M='$m' ");
WHILE ($a = mysql_fetch_array($result)) {
$member[] = $a['name'];
}//close while

//search the user database for all names
$result2 = mysql_query (SELECT * FROM tbl WHERE T = '$t' ");
WHILE ($b = mysql_fetch_array($result2)) {
$user = $b['name'];
$flag = 0;
//take the first username found in the WHILE loop and enter the FOR loop. Let the FOR loop check that first username against all the member names. If a match is found set the flag to 1 (and exit).

for ($i=0; $i<=count($member); $i++) {

if ($user == $member[$i] ) $flag= 1;

// If the flag is still set to 0, no matching name was found and the username should be deleted.
if $flag=0 {
mysql_query ("DELETE FROM tbl WHERE Name = '$user'")
}

}//end for

}//end while

claire

Sigh....nope...
copied your script exactly, but it still doesn't delete a user name which isn't in the member db.

I really thought moving the end of the for loop would do the trick...

I thought this little script would be trivial!! HA, was I wrong...

//search the member database for all names

$result=mysql_query("SELECT * FROM tbl WHERE M='$m' ");

WHILE ($a = mysql_fetch_array($result)) {

$member[] = $a['name'];

}//close while

//search the user database for all names

$result2 = mysql_query (SELECT * FROM tbl WHERE T = '$t' ");

WHILE ($b = mysql_fetch_array($result2)) {

$user = $b['name'];

$flag = 0;

//take the first username found in the WHILE loop and enter the FOR loop. Let the FOR loop check that first username against all the member names. If a match is found set the flag to 1 (and exit).

for ($i=0; $i<=count($member); $i++) {

if ($user == $member[$i] ) $flag= 1;

// If the flag is still set to 0, no matching name was found and the username should be deleted.

if $flag=0 {

mysql_query ("DELETE FROM tbl WHERE Name = '$user'")

}

}//end for

}//end while

Anon

Let's see if we can get to the other side of this page 🙂

Have you tried echoing out the select statements and then running them through the mysql command line to make sure you get the expected results?

Try print_r($member) after its set to make sure its got the right values

Are you sure your coloumn name's right(Name)
WHERE Name = '$user'

I get the feeling someone's going to come along and point out a really silly mistake.

Anon

if $flag=0 {
should be
if ($flag==0) {

Let me try to get your problem correctly. Let's say

The M field represents country and the T field represents age. And let's say that
$m = "Canada"
$t = "18"

Are you trying to delete rows that DO NOT have M AND T as those values? In other words, are you trying to keep the rows that match both of those criteria?

If I got the problem right, then you can replace all that code with this query:

DELETE FROM tbl WHERE M!='$m' OR T!='$t'

HTH,

Diego

claire

Ah, found at least one SIMPLE error! the FOR loop must start from $i=0; not 1, since the first array is [0]!

(Found that out when the first member name didn't echo inside the FOR loop!)

For test purposes I have two names in each db. One name is the same. This is what I get when I echo:

The print_r($member) after the member WHILE loop => echos both names. OK!

The echo $user; inside the user WHILE loop => echos both names. OK!

Trying to echo $member[$i] or $user inside any of the if ($flag= ) statements => nothing

Echoing $user inside the FOR loop => user1, user1, user1, user2, user2, user2
(why three times? It should test the first with both member names and then the second with both member names = two times each)

Echoing $member inside the FOR loop => member1, member2, member1, member2. OK!

claire

Hi Diego,

not quite so. This is an application for my condominium association. People buy an appartement and becomes members. When they move in they also become users.
Usually members and users are the same. But sometimes parents buy apartements for their kids. Thus member names and user names are different.
Sometimes a single person buys an apartement and as times goes by becomes cohabitant or married. Thus two users - only one member for the same apartement.

I have done the following:
When an apartement has been sold I change the member names to the new owners names. When they move in I automatically delete all user names for that apartement and through a checkbox form insert those member names that also becomes users.
By doing this I only need to write the names once.
But deleting all user names automatically isnt ok in the case when someone marries and the spouse becomes a new owner and user. When I move the new name from the member db to the user db I dont want to delete the old name (the one who still lives in the apartement). If I delete that name I also loose every other information for that entry (phone no, mailaddresses etc)

Sorry for the lenghty reply - hope this makes sense

claire

Finally got it to work!

Thanks Martin for all time spent on helping me.
The clue was to
1) end the FOR loop after the $flag =1;

Once the flag is set we don't need to do any more comparison, don't want to risk the flag to be set to 0 again.
2) change if ($flag = 0) { to if ($flag == 0)
this time it really is a comparison!

crusty_php

Well done Claire!