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mysql_field_table

jorge at rhst dot net
29-Jul-2007 02:57


The function below takes a function and returns the col->table mapping as an array.



For example:



$query = “SELECT a.id AS a_id, b.id b_id FROM atable AS a, btable b”



$cols  = queryAlias($query);



print_r($cols);



Returns:



Array

(

    [a] => atable

    [b] => btable

)



I can't promise it's perfect, but this function never hit production cause I ended up using mysqli methods instead.



Enjoy

-Jorge



  /**

   * Takes in a query and returns the alias->table mapping.

   *

   * @param string $query

   * @return array of alias mapping

   */

  

  function queryAlias ( $query ) {

    

    //Make it all lower, we ignore case

    $substr = strtolower($query);

    

    //Remove any subselects

    $substr = preg_replace ( ‘/\(.*\)/’, ”, $substr);

   

    //Remove any special charactors

    $substr = preg_replace ( ‘/[^a-zA-Z0-9_,]/’, ‘ ‘, $substr);

    

    //Remove any white space

    $substr = preg_replace(‘/\s\s+/’, ‘ ‘, $substr);

    

    //Get everything after FROM

    $substr = strtolower(substr($substr, strpos(strtolower($substr),‘ from ‘) + 6));

    

    //Rid of any extra commands

    $substr = preg_replace(

                Array(

                    ‘/ where .*+$/’,

                    ‘/ group by .*+$/’,

                    ‘/ limit .*+$/’ ,

                    ‘/ having .*+$/’ ,

                    ‘/ order by .*+$/’,

                    ‘/ into .*+$/’

                   ), ”, $substr);

    

    //Remove any JOIN modifiers

    $substr = preg_replace(

                Array(

                    ‘/ left /’,

                    ‘/ right /’,

                    ‘/ inner /’,

                    ‘/ cross /’,

                    ‘/ outer /’,

                    ‘/ natural /’,

                    ‘/ as /’

                   ), ‘ ‘, $substr);

    

    //Replace JOIN statements with commas

    $substr = preg_replace(Array(‘/ join /’, ‘/ straight_join /’), ‘,’, $substr);

    



    $out_array = Array();

    

    //Split by FROM statements

    $st_array = split (‘,’, $substr);

  

    foreach ($st_array as $col) {

      

      $col = preg_replace(Array(‘/ on .*+/’), ”, $col);

      

      $tmp_array = split(‘ ‘, trim($col));

      

      //Oh no, something is wrong, let’s just continue

      if (!isset($tmp_array[0]))

        continue;

        

      $first = $tmp_array[0];

      

      //If the “AS” is set, lets include that, if not, well, guess this table isn’t aliased.

      if (isset($tmp_array[1]))

        $second = $tmp_array[1];

        else  

        $second = $first;

        

      if (strlen($first))

       $out_array[$second] = $first;

      

    }

    

    return $out_array;

  }

spam at blondella dot de
03-Oct-2006 04:09


<?php

/*

this function might help in the case described above :-)

*/

function mysql_field_table_resolve_alias($inQuery,$inResult,$inFieldName) {

   $theNameOrAlias = mysql_field_table($inResult,$inFieldName);

   //check, if AS syntax is being used

   if(ereg(" AS ",$inQuery))  {

      //catch words in query

      $theWords = explode(" ",ereg_replace(",|\n"," ",$inQuery));

      //find the words preceding and following AS

      foreach($theWords as $theIndex => $theWord)  {

         if(trim($theWord) == "AS"

         && isset($theWords[$theIndex-1])

         && isset($theWords[$theIndex+1])

         && $theWords[$theIndex+1] == $theNameOrAlias

         ) {

            $theNameOrAlias = $theWords[$theIndex-1];

            break 1;

         }

      }

   }

   return $theNameOrAlias;

}

?>

me at thomaskeller dot biz
23-Nov-2005 01:15


Beware that if you upgrade to MySQL 5 from any earlier version WITHOUT dumping and reloading your data (just by keeping the binary data in MyISAM table files), you might get weird output on the "table" value for mysql_fetch_field and in this function. Weird means that the table name is randomly set or not.



This behaviour seems to popup only if the SQL query contains a ORDER BY clause. A bug is already reported: 



http://bugs.mysql.com/bug.php?id=14915



To prevent the issue, dump and reload all participating tables in your query or do



CREATE TABLE tmp SELECT * FROM table;

DROP TABLE table;

ALTER TABLE tmp RENAME table;



on each one via commandline client.

cptnemo
14-Aug-2004 07:18


When trying to find table names for a (My)SQL query containing 'tablename AS alias', mysql_field_table() only returns the alias as specified in the AS clause, and not the tablename.

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