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mysql_list_fields — Listet MySQL Ergebnisfelder auf
Hinweis:
Die Funktion mysql_list_fields() ist veraltet. Stattdessen ist es vorzuziehen mit der Funktion mysql_query() den SQL-Befehl SHOW COLUMNS FROM table [LIKE 'name'] auszuführen.
mysql_list_fields() fordert Information über den angegebenen Tabellennamen an. Argumente sind der Datenbankname und der Tabellenname. Die zurückgelieferte Ergebnis-Kennung kann von den Funktionen mysql_field_flags(), mysql_field_len(), mysql_field_name() und mysql_field_type() verwendet werden.
Beispiel #1 Alternative zum veraltetenmysql_list_fields()
<?php
$result = mysql_query("SHOW COLUMNS FROM sometable");
if (!$result) {
echo 'Abfrage konnte nicht ausgeführt werden: ' . mysql_error();
exit;
}
if (mysql_num_rows($result) > 0) {
while ($row = mysql_fetch_assoc($result)) {
print_r($row);
}
}
?>
Das oben gezeigte Beispiel liefert eine ähnliche Ausgabe wie:
Array
(
[Field] => id
[Type] => int(7)
[Null] =>
[Key] => PRI
[Default] =>
[Extra] => auto_increment
)
Array
(
[Field] => email
[Type] => varchar(100)
[Null] =>
[Key] =>
[Default] =>
[Extra] =>
)
Für Abwärtskompatibilität kann mysql_listfields() verwendet werden. Diese Funktion ist jedoch veraltet.
Siehe auch mysql_field_flags() und mysql_info().
Every my html table output begins with heading row containing the field names. For that purpose I accepted the short combination of MySQL function, giving me a result similar to the mysql_fetch_array() for the row of values. The following example shows the basic idea. It should be adapted for the specific use:
<?php
//...
$field_names = array_keys( mysql_fetch_array( mysql_query( $query, $link), MYSQL_ASSOC));
//...
?>
The advantage of this is, that it gives the names of the result, neither the field names of the whole table.
Please read the discussion about duplicate field names in SQL result carefully. The use, as shown in the example above, increments the pointer, hence some regular function, which does not, could be more useful :-)
Jan
Note, using mysql_list_fields will change the currently selected database so subsequent mysql_query operations will be on the database in param 1 not the one selected with mysql_select_db
To make an array containing the names of a column from a table, you use the following simple script: (Note: using table1 with three columns)
<?php
$qColumnNames = mysql_query("SHOW COLUMNS FROM table1",$db) or die("mysql error");
$numColumns = mysql_num_rows($qColumnNames);
$x = 0;
while ($x < $numColumns)
{
$colname = mysql_fetch_row($qColumnNames);
$col[$colname[0]] = $colname[0];
$x++;
}
print_r($col);
/* it will have the following output
Array (
[firstcolumn] => firstcolumn
[secondcolumn] => secondcolumn
[thirdcolumn] => thirdcolumn
)
*/
?>
Or you can number the columns from zero. This help when using it in conjunction with mysql_fetch_row to get an array. You don't have to remember which number of the array a certain column is.
<?php
$qColumnNames = mysql_query("SHOW COLUMNS FROM table1",$db) or die("mysql error");
$numColumns = mysql_num_rows($qColumnNames);
$x = 0;
while ($x < $numColumns)
{
$colname = mysql_fetch_row($qColumnNames);
$col[$colname[0]] = $x;
$x++;
}
print_r($col);
/* it will have the following output
Array (
[firstcolumn] => 0
[secondcolumn] => 1
[thirdcolumn] => 2
)
*/
?>
To use it in conjuction with mysql_fetch_row:
<?php
$row = mysql_fetch_row("SELECT * from table1",$db) or die("mysql error");
?>
You can now call $row[col[firstcolumn]]. This becomes useful when you have a lot of columns.
If you're willing to use a lot of functions to get a little information about fields in a table, this function is for you. If you just want to get all the information you can find, you can use this:
<?php
// Taken from: http://ca.php.net/manual/en/function.mysql-field-flags.php
// Original by: amir at scrounch dot com
// Returns the name of the fields in the primary key for a table.
// Also keeps the fields in KEY order. Handy.
function getPrimaryKeyOf($table) {
$keys = Array();
$query = sprintf("SHOW KEYS FROM `%s`", $table);
$result = mysql_query($query) or die(mysql_error());
while ($row = mysql_fetch_assoc($result)) {
if ( $row['Key_name'] == 'PRIMARY' )
$keys[$row['Seq_in_index'] - 1] = $row['Column_name'];
}
return $keys;
}
// Returns a bunch of information about a table...
// The name of the auto-increment field, if any, fields in the
// primary key (using the function above), and all information
// about all fields.
function getTableInformationOf($table) {
$information = array(
"auto" => "",
"primary" => array(),
"fields" => array()
);
$information['primary'] = $this->getPrimaryKeyOf($table);
$result = mysql_query("DESC `$table`");
while ( $field = mysql_fetch_assoc($result) ) {
$information['fields'][] = $field;
if ( $field['Extra'] == "auto_increment" )
$information['auto'] = $field['Field'];
}
return $information;
}
?>
mysql_list_fields() retrieves information about the given table name but you can use something like mysql_fetch_field to retrieve the field names from a result source.
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