coding fuctions

TweetyPie

Can someone explain what the following line of codes perform? these are seperate bits of code, i have numbered each line seperatly.


1) <form method=post action="<? echo $_SERVER['PHP_SELF']; ?>">


2) if (isset($_POST['submit'])){

3) $sql = "select * from users where name = '" . $_POST['username'] . "';";

4) if ($row["password"] == $_POST['password']) {



5) $sql1 = "SELECT j_num, j_title from job WHERE job.fk_depart = '$id'";
        $query1 = mysql_query($sql1) or exit ("Error in query: $sql1. " . mysql_error());
        while(list($jnum, $jtitle) = mysql_fetch_row($query1))



6) <form action="<? echo $_SERVER['PHP_SELF']; ?>" method="POST">

7) $errorList = array();
$list = 0;

if (empty($jnum))
{ $errorList[$list] = "Invalid entry: Job code"; $list++; }

if (empty($jtitle))
{ $errorList[$list] = "Invalid entry: Job Title"; $list++; }

if (empty($jresp))
{ $errorList[$list] = "Invalid entry: Responsibilities"; $list++; }

if (empty($jreq))
{ $errorList[$list] = "Invalid entry: Qualifications"; $list++; }

if (empty($jcont))
{ $errorList[$list] = "Invalid entry: Contact"; $list++; }

if (empty($contmail) || mail_check($contmail))
{ $errorList[$list] = "Invalid entry: Contact Email "; $list++; }

    if (sizeof($errorList) == 0)



8) if(!isset($submit))


9) if (!isset($jnum) || $jnum == "")

10) if(!isset($skills) && !isset($opr) && !isset($years))
                {

            $sql .= " AND personal.p_id = skill.p_id  AND (";
                           $keywords = split(" ", $skills);
                                   for ($x=0; $x<sizeof($keywords); $x++)
                    {
                    trim($keywords[$x]);

  if($x != 0)
                            {
                            $query .= " AND";
                            }
                    $sql .= " (skill.skill LIKE '%" . $keywords[$x] ."%' AND skill.exper " .  $opr . $years . " )";
                    }
            $sql .= ")";
            }

steadyguy

1) prints the name of the current document into the action attribute of the HTML form element

2) Checks to see if the user has submitted a variable called submit via the HTTP POST method.

3) Composes an SQL query with data stored in the variable username submitted via the HTTP POST method.

4) Checks to see if value at key password in array $row is equal to a variable called password that has been submitted via the HTTP POST method.

5) Composes and runs a conditional SQL query. If the query is unsuccessful, script ends and you get the error returned by MySQL. If successful, cycles through the result set, assigning $jnum, and $jtitle to corresponding values in a row of this result set. [Personal opinion: there are more intuitive (and probably also faster) ways to do this.]

6) Same as 1)

TweetyPie

i have a few more that im not to clear on.

1) $sql = "SELECT DISTINCT d_id, dep from depart, job WHERE depart.d_id = job.depart";

what does the DISTINCT function as or do?

2) while(list($id, $dep) = mysql_fetch_row($query))

For this code, is the following correct? it retrieves data each call to the mysql_fetch_row fetches the next row of results and returns an array. The attributes are then stored in the arrary 'list'.??

3) <form method=post action="<? echo $_SERVER['PHP_SELF']; ?>">

what does $_SERVER and ['PHP_SELF'] perform in this line of code?

4) while ($row=mysql_fetch_array($query)) {

Is this the same as while ($row=mysql_fetch_row($query)) {
what is the difference between the two?

5) what does a '.' mean in the code, For example:
$sql = "SELECT DISTINCT d_id, dep from depart, job WHERE depart.d_id = job.depart";

where it says depart.d_id, what does the ' . ' mean?

6) ($num_rows) 
what does this mean/ do?

and unset($num_rows)

what does this do?

richmlpdx

1) $sql = "SELECT DISTINCT d_id, dep from depart, job WHERE depart.d_id = job.depart";

what does the DISTINCT function as or do?

The DISTINCT keyword is used to return only distinct (different) values of the d_id column.

steadyguy

Many of the answers to your questions can be found in the manual. However ...

1) An SQL query with DISTINCT(column_name) will return only results where column_name is different from all the other values in the column. If there are more than one value in column_name share the same value, then it will return just one of them - usually the first one it encounters.

2) No. list() is a function. It assigns the values from the right side of the = to the variables passed to the function by position ($id and $dep in this case).

3) 'PHP_SELF' is a key name in the superglobal array $_SERVER. It's value is the name of the current document.

4) Not quite. mysql_fetch_array() is quite a bit faster, and recommended if you're fetching more than one or two rows. Unless you specify otherwise, mysql_fetch_array() returns both an indexed and an associative array of the current row of the result set. mysql_fetch_row() only returns an indexed array.

5) The dot (.) is called a qualifier it tells the database that you mean the d_id column of the depart table. If there is no doubt as to which one you mean, you can leave it and the table name out, but is required if there is more than one column with that name referenced in the query, and makes your life easier if you're SELECTing from more than one table.

6) B [/B] does nothing of value. unset() removes the value of the variable passed to it. If you asked for $num_rows after calling unset() on it, it would return with a null value (ie., the empty string: '').