MySQL 函数
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mysql_field_flags

(PHP 4, PHP 5)

mysql_field_flags — 从结果中取得和指定字段关联的标志

说明

string mysql_field_flags ( resource $result , int $field_offset )

mysql_field_flags() 返回指定字段的字段标志。每个标志都用一个单词表示，之间用一个空格分开，因此可以用 explode() 将其分开。

如果 MySQL 版本足够新，则会支持以下的标志："not_null", "primary_key", "unique_key", "multiple_key", "blob", "unsigned", "zerofill", "binary", "enum", "auto_increment", "timestamp"。

为向下兼容仍然可以使用 mysql_fieldflags()，但反对这样做。

MySQL 函数
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PHP手册

用户评论:

play at arcadevillage dot com (2009-08-03 07:07:12)

To really backup the database values, I made a little changement :

My code really looks like bomas 's code, but there is an important diffence :

<?php
$nbc = mysql_num_fields($req_table);
while ($ligne = mysql_fetch_array($req_table))
  {
    $insertions = "INSERT INTO $table VALUES(";
     for ($i=0; $i<$nbc; $i++)
        {
          if ( $i > 0 ) $insertions .= ", ";
          if ( !isset($ligne[$i])) 
            $insertions .= "NULL";
          else
            $insertions .= "'" . mysql_real_escape_string($ligne[$i]). "'";
        }
     $insertions .= ");";
     $dumpsql[] = $insertions;
   }
?>

$dumpslq is the variable where I put the insertion orders before writting them in a text file.

Before, I test that the values if not NULL into the field because it is the only way to make the difference, for example for string text fields, between NULL values and empty strings.

If you don't make this test, you should find empty string instead of NULL values when you do the backup.

Bob (2009-05-05 03:00:00)

To parse an enum/set type correctly, including strings like ENUM('a\'b','c'), here is an almost pcre-free way that works well.
<?php
function parse_enum_values($typestr)
{
    // remove ENUM/SET part
    $typestr = preg_replace('/^(enum|set)/i', '', $typestr);
    // trim '(', ')', ' off the ends of the string and then explode it on ','
    return trim(explode("','", $typestr), "(')");
}
?>
It works because explode is looking for ',' - not ',\'.

dev at rgbworld dot com (2008-04-13 15:45:12)

With regard to get_fields() by pike-php at kw dot nl
For 'enum and 'set' the code improperly parses single quote marks that should be allowed in the elements.
For example EMUM('a\'s', 'b') is parsed into 3 array elements when it should be 2.
Wrong:
[args] => Array
(
[0] => a
[1] => s
[2] => b
)
It should give:
[args] => Array
(
[0] => a's
[1] => b
)
I am not good with preg, but if someone could provide a solution, that would be great. Thank you!

bomas at cities-of-faith dot com (2005-09-08 01:52:43)

well, to make a complete backup of your database, i suggest this code:
//open database here
$tab_status = mysql_query("SHOW TABLE STATUS");
while($all = mysql_fetch_assoc($tab_status)):
$tbl_stat[$all[Name]] = $all[Auto_increment];
endwhile;
unset($backup);
$tables = mysql_list_tables('cofadmin');
while($tabs = mysql_fetch_row($tables)):
$backup .= "--\n--Tabel structuur voor `$tabs[0]`\n--\n\nDROP IF EXISTS TABLE `$tabs[0]`\nCREATE TABLE IF NOT EXISTS `$tabs[0]` (&nbsp;";
$res = mysql_query("SHOW CREATE TABLE $tabs[0]");
while($all = mysql_fetch_assoc($res)):
$str = str_replace("CREATE TABLE `$tabs[0]` (", "", $all['Create Table']);
$str = str_replace(",", ",&nbsp;", $str);
$str2 = str_replace("`) ) TYPE=MyISAM ", "`)\n ) TYPE=MyISAM ", $str);
$backup .= $str2." AUTO_INCREMENT=".$tbl_stat[$tabs[0]].";\n\n";
endwhile;
$backup .= "--\n--Gegevens worden uitgevoerd voor tabel `$tabs[0]`\n--\n\n";
$data = mysql_query("SELECT * FROM $tabs[0]");
while($dt = mysql_fetch_row($data)):
$backup .= "INSERT INTO `$tabs[0]` VALUES('$dt[0]'";
for($i=1; $i<sizeof($dt); $i++):
$backup .= ", '$dt[$i]'";
endfor;
$backup .= ");\n";
endwhile;
$backup .= "\n-- --------------------------------------------------------\n\n";
endwhile;
echo $backup;
this displayes your data the same way as phpmyadmin does.
hope it helps some of you guys
Greetz

pike-php at kw dot nl (2005-07-14 16:55:40)

ok, sorry for the code bloat :) but this is how I 
get the full power of mysql's DESCRIBE table statement, in 
an associative array, including defaults, enum values, float radix et all.

it assumes mysql returns the type as 
   "type[(arg[,arg..])] [ add]"
like
   "float(20,6) unsigned"
   "enum('yes','no')"
etc

<?

function getFields($tablename) {
    
        $fields = array();
        $fullmatch         = "/^([^(]+)(\([^)]+\))?(\s(.+))?$/";
        $charlistmatch     = "/,?'([^']*)'/";
        $numlistmatch     = "/,?(\d+)/";
        
        $fieldsquery .= "DESCRIBE $tablename";
        $result_fieldsquery = mysql_query($fieldsquery) or die(mysql_error());
        while ($row_fieldsquery = mysql_fetch_assoc($result_fieldsquery)) {
            
            $name     = $row_fieldsquery['Field'];
            $fields[$name] = array();
            $fields[$name]["type"]         = "";
            $fields[$name]["args"]         = array();
            $fields[$name]["add"]          = "";
            $fields[$name]["null"]        = $row_fieldsquery['Null'];
            $fields[$name]["key"]        = $row_fieldsquery['Key'];
            $fields[$name]["default"]    = $row_fieldsquery['Default'];
            $fields[$name]["extra"]        = $row_fieldsquery['Extra'];
            
            $fulltype     = $row_fieldsquery['Type'];
            $typeregs = array();
            
            if (preg_match($fullmatch, $fulltype, $typeregs)) {
                $fields[$name]["type"] = $typeregs[1];
                if ($typeregs[4]) $fields[$name]["add"] = $typeregs[4];
                $fullargs = $typeregs[2];
                $argsreg = array();
                if (preg_match_all($charlistmatch, $fullargs, $argsreg)) {
                    $fields[$name]["args"] = $argsreg[1];
                } else {
                    $argsreg = array();
                    if (preg_match_all($numlistmatch, $fullargs, $argsreg)) {
                        $fields[$name]["args"] = $argsreg[1];
                    } else die("cant parse type args: $fullargs");
                }
            } else die("cant parse type: $fulltype");

        }
        return $fields;
            
    }

?>

buttrose at unimelb dot edu dot au (2004-10-20 19:26:52)

This function is essential for writing a generic table editor (ie one that just takes the name of the table and works out what fields it has, types, sizes etc.). Unfortunately, I am using psotgreSQL not mySql. Postgres has field_type and field_size functions but not as far as I can tell an equivalent of the mysql_field_flags() function. Without it, there is no way I can do generic ADDs and INSERTs.
Anyone know a workaround to get this information (eg is the field a primary key? Can it be NULL? Is it auto_increment?) in Postgres?
Cheers
Rob Buttrose

amir at scrounch dot com (2003-08-17 10:39:38)

returns primary keys of a table using 'show keys'
although it is possible to use desc, show keys offers possible enhancements such a getting sequence in index along with it
function getPrimaryKeyOf($table, $link) {
$pk = Array();
$sql = 'SHOW KEYS FROM `'.$table.'`';
$res = mysql_query($table, $link) or die(mysql_error());
while ($row = mysql_fetch_assoc($res)) {
if ($row['Key_name']=='PRIMARY')
array_push($pk, $row['Column_name']);
}
return $pk;
}

simone dot t at betisgroup dot com (2003-04-10 04:20:32)

Another examples :
####################################
function field_keys($host, $user, $password, $database, $field ) {
$db_link = mysql_connect($host, $user, $password) or die ("error connect");
mysql_select_db($database,$db_link);
$query="DESC $field";
$results=mysql_query($query);
$i=0;
while ($row=mysql_fetch_array($results)) {
if ($row[Key]=="PRI") {
$array_keys[$i]=$row[Field];
}
$i++;
}
return $array_keys;
}
####################################
//Example of Main...
$tmp = field_keys("localhost", "myuser", "mypassword", "mydb", "field_name" );
// ...loop through array...
foreach ( $tmp as $array_tmp){
print "<br>";
print $array_tmp;
print "<br>";
}

justin DOT flavin AT ntlworld DOT com (2002-12-06 10:36:20)

Sometimes, when writing a generic function or class, you want your script to be able to determine what the primary key of a table is.
/* usual MySQL stuff */
$query="DESC UsersTable";
$results=mysql_query($query);
while ($row=mysql_fetch_array($results))
{
if ($row[Type]="PRI")
{
print "I found the primary key! <br>";
$UserKey=$row[Field];
print $row[Field];
/* drop out , as we've found the key */
exit;
}
}
..... later on we might have something like
< some sort of loop through records >
print "<a href='View_User_record.php?userkey=$UserKey'> Users Name </a>";
<end loop>
What's also interesting is the useful data you can get from
a DESC query.
The following prints out the array values grabbed by mysql_fetch_array on a DESC query - VERY useful stuff!!!
/* usual MySQL stuff */
$query="DESC UsersTable";
$results=mysql_query($query);
while ($row=mysql_fetch_array($results))
{
print "<pre>";
print_r ($row);
print "</pre>";
}

jakemsr at jakemsr dot com (2002-10-31 00:32:45)

I didn't find anything to get the valid values for
ENUM or SET column types, so I came up with the
following
function mysql_enum_values($table, $field)
{
$sql = "SHOW COLUMNS FROM $table LIKE '$field'";
$sql_res = mysql_query($sql)
or die("Could not query:\n$sql");
$row = mysql_fetch_assoc($sql_res);
mysql_free_result($sql_res);
return(explode("','",
preg_replace("/.*\('(.*)'\)/", "\\1",
$row["Type"])));
}

cufarley at nirvanet dot net (2001-07-11 05:36:53)

Using the "DESC TableName" command may also do the trick and is a bit shorter.

jurgen at alienguitar dot com (2001-06-10 16:50:00)

The previous problem to get the default values of a column:
Use the following query and parse the 'Default' column:
"SHOW COLUMNS FROM TableName"
or for a single entry:
"SHOW COLUMNS FROM TableName LIKE 'column'"
It will give you also values for Type, Null, Key and Extra (check with mysql program first, so you see what you get ;-)

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