select item with composite key if there are items in data "using while"

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hi every one
I want know how I can select item from database when I have composite primary key

I have this table
sID cID item1
1 cs9 rr

when sID &cID are composite primary key
and item1 is what I want to select

and also I want use this code to select every items if there are items

PHP

<?php
$db_name="grade_book";
        $tbl_name="students_course";
        mysql_connect("localhost", "root", "");
        mysql_select_db("$db_name");
$sID=$_SESSION['sID'];
        $sql=mysql_query("SELECT * FROM course WHERE cID in(SELECT cID FROM $tbl_name WHERE sID=$sID)") or die(mysql_error());
        while($mysqlf =mysql_fetch_array($sql))
        {
            $chrs=$mysqlf['chrs'];
            //echo"$sid<br>";
            echo "$chrs<br>";

        }
?>

>>>> I know this select is wrong

Posted 29-May-11 14:37pm

malemar

Updated 29-May-11 17:39pm

Wild-Programmer

v3

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Comments

TorstenH. 30-May-11 2:49am

..so you have different items with different "sID" and "cID" and want to select them?
or are they listed behind "Item1" as "Item2", "Item3" and so on?

malemar 30-May-11 9:10am

no, I do not want to select "sID" & "cID"

eg. from this table
sID cID item1
1 cs9 rr
1 cs2 ee
2 cs3 ff

I want to select "items" as a list
eg.
rr
ee
ff

and
in the php file I have just "sID" as session

how I can select the list "items"?!!

malemar 30-May-11 13:17pm

do I need to explain more??

1 solution

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Maciej Los · Answer 1 · 2011-05-31T09:32:00

If example table has data as you wrote, you need to ask your database like this:

SQL

SELECT item1 FROM course WHERE sID = $sID

Return: single record.

SQL

SELECT DISTINCT item1 FROM course

Return: all (not duplicated) records listed in item1 column

If item1 is located in the other table, you should explain your database structure.