First post -- help a noob, please.

tefflox · 10-30-2007, 12:30 PM

hello, first post to the forums (my birthday here : )

so, I've established a database for the first time, on my own. I'm very excited to have done that. However, there's a lot to learn. The following script gives an error Unknown column 'category' in 'where clause'. This is all new to me. I've worked with php, but never with databases, only for rendering html.

PHP Code:


			
<?php



  $username = "root";

  $password = "-------";

  $database = "grav";

  $host     = "localhost";



    # connect to database

    $cid = mysql_connect($host,$username,$password);

    if (!$cid) { echo("ERROR: " . mysql_error() . "\n");    }

?>

<html>

 <head>

  <title>Display Posts</title>

 </head>

 <body>

 

<?php

    $category = "Posts";



    # setup SQL statement

    $SQL = " SELECT * FROM grav ";



    # execute SQL statement

    $retid = mysql_db_query($database, $SQL, $cid);



    # check for errors

    if (!$retid) { echo( mysql_error()); }

      else {



          # display results

          echo ("<h3><b>$category</b></h3>\n");

           while ($row = mysql_fetch_array($retid)) {

              $post = $row["post"];

              echo ($post."<br/>\n");

          }

    }

?>



</body>

</html>

I also welcome you to read this entry at pmd...

abduraooft · 10-30-2007, 12:42 PM

This is a usual error which comes when we try to access a field-name not in the specified table.
but your query is $SQL = " SELECT * FROM grav "; , no reference to a field named category.
Do you have any other query there?

tefflox · 10-30-2007, 01:00 PM

Code:

$SQL = " SELECT * FROM grav WHERE category = '$category' ";

but it throws the same error. actually, i don't know what 'category' refers to.

abduraooft · 10-30-2007, 01:37 PM

To use the above query, you must have a field named 'category' in the table named 'grav'. Check your table structure.

tefflox · 10-30-2007, 01:45 PM

the db is 'grav', the table is 'posts' the fields are the int key and 'post' field.

all this does is echo the h3 element. thank for your patience.

PHP Code:


			
<?php

    $category = "post";



    # setup SQL statement

    $SQL = " SELECT * FROM posts WHERE post = '$category' ";



    # execute SQL statement

    $retid = mysql_db_query($database, $SQL, $cid);



    # check for errors

    if (!$retid) { echo( mysql_error()); }

      else {



          # display results

          echo ("<h3><b>$category</b></h3>\n");

           while ($row = mysql_fetch_array($retid)) {

              $post = $row["post"];

              echo ($post."<br/>\n");

          }

    }

?>

Fumigator · 10-30-2007, 04:01 PM

Quit using mysql_db_query(); it is deprecated.

Use mysql_query() instead.

tefflox · 10-30-2007, 04:12 PM

I got the following code to work; however, changing to mysql_query() throws this error: Warning: Wrong parameter count for mysql_query(). Also, I am befuddled why $post = $row[$i++]; does not work.

PHP Code:


			
<?php

    $category = "post";



    # setup SQL statement

    $SQL = " SELECT post FROM posts";



    # execute SQL statement

    $retid = mysql_db_query($database, $SQL, $cid);



    # check for errors

    if (!$retid) { echo( mysql_error()); }

      else {



          # display results

          echo ("<h3><b>Posts</b></h3>\n");

          $i = 0;

           while ($row = mysql_fetch_array($retid)) {

              $post = $row[$i];

              echo ("<p>".$post."</p>\n");

          }

    }

?>

Fumigator · 10-30-2007, 04:32 PM

I did not give you a link to the mysql_query() page in the PHP manual for my own health, I gave you the link so you would click on it and determine which arguments it requires (and how many).

matak · 10-30-2007, 04:45 PM

Quote:

Originally Posted by tefflox

PHP Code:


			
while ($row = mysql_fetch_array($retid)) {
              
//try this
echo $row[0];

                    // $post = $row[$i];
          //    echo ("<p>".$post."</p>\n");
          }
    }
?>

you can access your posts with $row[0]. in your case it would be post table field.

and as for i++, just imagine it is done, and you'll be fine.

if you are selecting only one row then it's easier to use mysql_fetch_row...

BWiz · 10-30-2007, 04:46 PM

1) You need to establish a connection with the server
2) You need to select which database you're going to be using
3) Then, you need to construct a query
example:
if the TABLE name is "posts" and there is a field in it called
"name", then the query to select the names of all the people
who posted would be:

PHP Code:


			
       $query = "SELECT name FROM posts";

Example script:

PHP Code:


			
<?php
  $host = "localhost";
  $user = "bwhite";
  $pass = "password";
  $db_name = "cwaf";

  $connection = @mysql_connect( $host, $user, $pass ) 
                      or die ( mysql_error() );
  $db_connect = @mysql_select_db( $db_name )
                      or die ( mysql_error() );

  $query = "SELECT name FROM posts";
  $result = mysql_query ( $query );
  
  //Now do what you would with the received data (should it exist).
?>

aedrin · 10-30-2007, 05:20 PM

Try using this to access your rows.

PHP Code:


			
$result = mysql_query($query);



while ($row = mysql_fetch_assoc($result)) {

    echo $row['post'];

}

Notice the use of mysql_fetch_assoc(). And instead of using $row[0], etc. you can use the actual name of the column.

This improves code readability and maintainability.