Relationship

Anon

Ive seen the code somewhere before which allows to do make a relationship between 2 tables using php and mysql but i cant find the code newhere now. What is the mysql_query i would have to run in php to get it to work.

hankster

Are you trying to get data based on multiple tables? If so then you might want to use some type of join, you can find the info on join here: http://www.mysql.com/doc/J/O/JOIN.html.
Or search the archives for it. If not then can you give greater detail on what you are trying to do.

Thanks,
H

Anon

Hallo,

1.First try to understand what RDBMS is. http://vip.hex.net/~cbbrowne/rdbms.html

Understand what Relationship is and why we use it?
Data is stored in different tables to minimize redundency. To have that there must be relationship between these tables. A relationship can be one-to-one, one-to-many and man-to-many.

The most common are one-to-many and one-to-one.

Let me consider one-to-many case.
table1 contains a field named ID as unique identifier of each record ,i.e, as a primary key. table2 contains ID as foreign key.

To get records from these two tables,

select * from table1, table2 where table1.ID = table2.ID;

Cheers;
Solomon

hankster

Thanks Solomon,
I did not fully understand the question. Good response!

Anon

Unfortunatelly, it was not for you. Sorry very much. I taught that I have responded to Darkness,
OK?

Solomon

hankster

You did, but it was a good point! No problem no harm intended ;-]

Anon

I have the code

$result = mysql_query( "SELECT * FROM hwkset,hwksheet WHERE hwkset.hwksheet = hwksheet.hwksheet AND hwkset.sets < '8-0'" );
while ( $a_row = mysql_fetch_array( $result )){
?>
<tr>
<td><?echo $a_row[sets]?></td><td><?echo $a_row[dayset]?></td><td><?echo
$a_row[subject]?></td><td><?echo $a_row[staff]?></td><td><?echo $a_row[hwkset]?></td></tr>
<?
}

There are no error msg's but no information is being displayed. There is information in the database. From what i can see it isnt running the while loop though.

What i have is 2 tables, 1 for homework set and another for homework sheets and what i need to do is display the homework but if there is a sheet that goes with it have it displaying the sheet as well.

Anon

OK!!!

Let us assume these two tables: homework and sheet.

HomeWorkID is primary key in homework table and forein key in sheet table.

Now,

$query = "select * from homework, sheet where homework.HomeWorkID = sheet.HomeWorkID";
$result = mysql_query($query);
while($data = mysql_fetch_object($result)){
echo "$data->Field1 --- $data->Field2----
}

You can put the result in table...