PHP: mysql_fetch_field

User Contributed Notes
mysql_fetch_field

creak at foolstep dot com
17-Jul-2003 05:26


Sorry, the last pattern doesn't work with type whithout length, so it would be better if you change it with this one :

    "^([a-zA-Z]+)\(?([^\)]*)\)?$"



It's still $type[1] for the type and $type[2] for the length.



Creak

blakjak at nospam dot com
27-Mar-2003 04:18


mysql_fetch_field will fail if your result set's internal pointer has advanced past the end of the result.



So, if you use ...



$result = mysql_query("select * from person where id=1"); // returns 1 row

$row = mysql_fetch_row($result);



while($field = mysql_fetch_field){

 echo $field->name;

}



... you won't see any fields.  If you need to use mysql_fetch_field, you need to do it before you've iterated through all the rows in the result set.

kflam at awc dot net dot au
18-Jun-2002 10:56


#Input: the table name and the enum field

#Output: an array that stores all options of the enum field or 

#false if the input field is not an enum

function getEnumOptions($table, $field) {

   $finalResult = array();



   if (strlen(trim($table)) < 1) return false;

   $query  = "show columns from $table";

   $result = mysql_query($query);

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

        if ($field != $row["Field"]) continue;

        //check if enum type

        if (ereg('enum.(.*).', $row['Type'], $match)) {

            $opts = explode(',', $match[1]);

            foreach ($opts as $item)

                $finalResult[] = substr($item, 1, strlen($item)-2);

        }

        else

                return false;

   }

   return $finalResult;

}



The function could be handy when making a selection option without typing all the options items respectively.

chrisshaffer at bellsouth dot net
06-Jun-2002 01:22


Slight error in the above comment:

$fieldLen = split("','",substr(1,-1,$fieldLen));



should read:

$fieldLen = split("','",substr($fieldLen,1,-1));



oops! ;)



I did take the above code (which saved me at least two hours worth of work), and massaged it into a function:



function mysql_enum_values($tableName,$fieldName)

{

  $result = mysql_query("DESCRIBE $tableName");



  //then loop:

  while($row = mysql_fetch_array($result))

  {

    //# row is mysql type, in format "int(11) unsigned zerofill"

    //# or "enum('cheese','salmon')" etc.



    ereg('^([^ (]+)(\((.+)\))?([ ](.+))?$',$row['Type'],$fieldTypeSplit);

    //# split type up into array

    $ret_fieldName = $row['Field'];

    $fieldType = $fieldTypeSplit[1];// eg 'int' for integer.

    $fieldFlags = $fieldTypeSplit[5]; // eg 'binary' or 'unsigned zerofill'.

    $fieldLen = $fieldTypeSplit[3]; // eg 11, or 'cheese','salmon' for enum.



    if (($fieldType=='enum' || $fieldType=='set') && ($ret_fieldName==$fieldName) )

    {

      $fieldOptions = split("','",substr($fieldLen,1,-1));

      return $fieldOptions;

    }

  }



  //if the funciton makes it this far, then it either 

  //did not find an enum/set field type, or it 

  //failed to find the the fieldname, so exit FALSE!

  return FALSE;



}



The most useful thing that I can think to do with this is to populate a HTML Dropdown box with it:



echo "<SELECT NAME=\"Select\" SIZE='1'>";

foreach($fieldOptions as $tmp)

{

  echo "<OPTION>$tmp";

}



Hope this helps  :D

justin at quadmyre dot com
18-Apr-2002 07:00


Same problem, slightly different solution.



$result = mysql_query("DESCRIBE tablename");

# or SHOW COLUMNS FROM

# or SHOW FIELDS FROM



then loop:



$row = mysql_fetch_array($result);

# row is mysql type, in format "int(11) unsigned zerofill"

# or "enum('cheese','salmon')" etc.



ereg('^([^ (]+)(\((.+)\))?([ ](.+))?$',$row['Type'],$fieldTypeSplit);

# split type up into array



$fieldType = $fieldTypeSplit[1]; # eg 'int' for integer.

$fieldFlags = $fieldTypeSplit[5]; # eg 'binary' or 'unsigned zerofill'.

$fieldLen = $fieldTypeSplit[3]; # eg 11, or 'cheese','salmon' for enum.



You might then like to:



if ($fieldType=='enum' or $fieldType=='set')

  $fieldLen = split("','",substr(1,-1,$fieldLen));



So for enum or set types, $fieldLen becomes an array of possible values.



Hope that helps someone out there...

php at brayra dot com
21-Mar-2002 06:09


I needed to get the field information and the enum/set values. Here is the function I created to expand the object returned by mysql_fetch_field. I also, decided to return all the fields for a table in an array of field objects by "name" and position much like mysql_fetch_array does.



You could test it by using:

$myfields = GetFieldInfo('test_table');

print "<pre>";

print_r($myfields);

print "</pre>";



The field objects now have 'len', 'values' and 'flags' parameters. 

NOTE: 'values' only has data for set and enum fields.



//This assumes an open database connection

//I also use a constant DB_DB for current database.

function GetFieldInfo($table)

{

  if($table == '') return false;

  $fields = mysql_list_fields(DB_DB, $table);

  if($fields){

    $columns = mysql_query('show columns from ' . $table);

    if($columns){

      $num = mysql_num_fields($fields);

      for($i=0; $i < $num; ++$i){

        $column = mysql_fetch_array($columns);

        $field = mysql_fetch_field($fields, $i);

        $flags = mysql_field_flags($fields, $i);

        if($flags == '') $flags=array();

        else $flags = explode(' ',$flags);

        if (ereg('enum.(.*).',$column['Type'],$match))

          $field->values = explode(',',$match[1]);

        if (ereg('set.(.*).',$column['Type'],$match))

          $field->values = explode(',',$match[1]);

        if(!$field->values) $field->values = array();

        $field->flags = $flags;

        $field->len = mysql_field_len($fields, $i);

        $result_fields[$field->name] = $field;

        $result_fields[$i] = $field;

      }

      mysql_free_result($columns);

    }

    mysql_free_result($fields);

    return $result_fields;

  }

  return false;

}



hope someone else finds this useful.

krang at krang dot org dot uk
10-Mar-2002 08:12


The field type returns what PHP classifies the data found in the field, not how it is stored in the database; use the following example to retrieve the MySQL information about the field....



$USERNAME = '';

$PASSWORD = '';



$DATABASE = '';

$TABLE_NAME = '';



mysql_connect('localhost', $USERNAME, $PASSWORD)

    or die ("Could not connect");



$result = mysql_query("SHOW FIELDS FROM $DATABASE.$TABLE_NAME");



$i = 0;



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

  echo $row['Field'] . ' ' . $row['Type'];

}

etiennesky at hotmail dot com
14-Oct-2001 03:55


If you need the 'Default' value of a column, you can use 









$meta->def 









to get it as in example 1.  







This has not been documented yet and can sure save others some time.

dave at techweavers dot net
04-Oct-2000 03:48


If you want to get the max length of a column not just the data use this:


$result = mysql_query ("SELECT * FROM table");


$fields = mysql_num_fields ($result);


$i = 0;


while ($i < $fields) {


$len   = mysql_field_len   ($result, $i);


$i++;


} 


Or refer to http://www.php.net/manual/function.mysql-field-type.php

mysql_fetch_field

Description

Parameters

Return Values

Examples

Notes

See Also