Solved

Describe 1 field

Posted on 2013-05-31
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Last Modified: 2013-06-18
Is it possible to only describe one field?

I've got a field called `state` in a table called `users`, so I would have thought I could use the statement:-
Describe `users` where `Field` = 'state';

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But all I get back is:-
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'where `Field` = 'state'' at line 1

If I use the statement:-
Describe `users`;

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I get all the rows, but I only want the 1 row returned.

Any ideas how I can complete this?

Thank you
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Comment
Question by:tonelm54
  • 2
4 Comments
 
LVL 40

Expert Comment

by:Kyle Abrahams
ID: 39210981
http://ss64.com/ora/desc.html

SELECT
column_name "Name",
nullable "Null?",
concat(concat(concat(data_type,'('),data_length),')') "Type"
FROM user_tab_columns
WHERE table_name='TABLE_NAME_TO_DESCRIBE'
and columnName = 'state'
0
 

Author Comment

by:tonelm54
ID: 39211002
That seems to point to using it in Oracle, which doesnt seem to work in MySQL.

Sorry, maybe I should have said I was using MySQL.
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LVL 40

Accepted Solution

by:
Kyle Abrahams earned 500 total points
ID: 39211236
http://stackoverflow.com/questions/4165195/mysql-query-to-get-column-names

Use this query:
SELECT `COLUMN_NAME`
FROM `INFORMATION_SCHEMA`.`COLUMNS`
WHERE `TABLE_SCHEMA`='yourdatabasename'
    AND `TABLE_NAME`='yourtablename';
    and 'Column_Name' = 'state'

you can look at information_schema to determine if you need other info from it.
0
 
LVL 109

Expert Comment

by:Ray Paseur
ID: 39218614
This is kind of old code and needs to be updated to remove the MySQL extension (explanation in the article).  You might tinker around with it to see how it works.  For obvious reasons I do not leave a copy on my server ;-)
http://www.experts-exchange.com/Web_Development/Web_Languages-Standards/PHP/PHP_Databases/A_11177-PHP-MySQL-Deprecated-as-of-PHP-5-5-0.html

<?php // RAY_mysql_SHOW_TABLES.php
error_reporting(E_ALL);
echo "<pre>\n"; // READABILITY FOR VAR-DUMPS


// DEMONSTRATE HOW TO GET INFORMATION ABOUT MySQL TABLES AND COLUMNS


// IMPORTANT PAGES FROM THE MANUALS
// MAN PAGE: http://php.net/manual/en/ref.mysql.php
// MAN PAGE: http://php.net/manual/en/mysql.installation.php
// MAN PAGE: http://php.net/manual/en/function.mysql-error.php


// CONNECTION AND SELECTION VARIABLES FOR THE DATABASE
$db_host = "localhost"; // PROBABLY THIS IS OK
$db_name = "??";        // GET THESE FROM YOUR HOSTING COMPANY
$db_user = "??";
$db_word = "??";



// OPEN A CONNECTION TO THE DATA BASE SERVER
// MAN PAGE: http://php.net/manual/en/function.mysql-connect.php
if (!$dbcx = mysql_connect("$db_host", "$db_user", "$db_word"))
{
    $errmsg = mysql_errno() . ' ' . mysql_error();
    echo "<br/>NO DB CONNECTION: ";
    echo "<br/> $errmsg <br/>";
}

// SELECT THE MYSQL DATA BASE
// MAN PAGE: http://php.net/manual/en/function.mysql-select-db.php
if (!$db_sel = mysql_select_db($db_name, $dbcx))
{
    $errmsg = mysql_errno() . ' ' . mysql_error();
    echo "<br/>NO DB SELECTION: ";
    echo "<br/> $errmsg <br/>";
    trigger_error('NO DATA BASE', E_USER_ERROR);
}
// IF WE GOT THIS FAR WE CAN DO QUERIES




// FINDING THE NAMES OF OUR TABLES
$sql = "SHOW TABLES";

// IF mysql_query() RETURNS FALSE, GET THE ERROR REASONS
// MAN PAGE:http://php.net/manual/en/function.mysql-query.php
if (!$res = mysql_query($sql, $dbcx))
{
    // MAN PAGE: http://php.net/manual/en/function.mysql-error.php
    $errmsg = mysql_errno() . ' ' . mysql_error();
    echo "<br/>QUERY FAIL: ";
    echo "<br/>$sql <br/>";
    die($errmsg);
}

// GET THE LIST OF TABLE NAMES
// MAN PAGE: http://php.net/manual/en/function.mysql-fetch-array.php
while ($show_tables = mysql_fetch_array($res))
{
    $my_tables[] = $show_tables[0];
}
if (empty($my_tables)) die('NO TABLES');
var_dump($my_tables);





// CHOOSE A TABLE AND GET THE COLUMN NAMES
$table_name = $my_tables[0];

$sql = "SHOW COLUMNS FROM $table_name";
if (!$res = mysql_query($sql, $dbcx))
{
    $errmsg = mysql_errno() . ' ' . mysql_error();
    echo "<br/>QUERY FAIL: ";
    echo "<br/>$sql <br/>";
    die($errmsg);
}
if (mysql_num_rows($res) == 0)
{
    echo "<br/>$table_name HAS NO COLUMNS";
}
else
{
    // MAN PAGE: http://php.net/manual/en/function.mysql-fetch-assoc.php
    while ($show_columns = mysql_fetch_assoc($res))
    {
        $my_columns[] = $show_columns["Field"];
        var_dump($show_columns);
    }
    var_dump($my_columns);
}





// CHOOSE A TABLE AND GET THE CREATE TABLE STATEMENT FOR IT
$table_name = $my_tables[0];

$sql = "SHOW CREATE TABLE $table_name";
if (!$res = mysql_query($sql, $dbcx))
{
    $errmsg = mysql_errno() . ' ' . mysql_error();
    echo "<br/>QUERY FAIL: ";
    echo "<br/>$sql <br/>";
    die($errmsg);
}
while ($show_creates = mysql_fetch_assoc($res))
{
    $my_creates[] = $show_creates["Create Table"];
}
var_dump($my_creates);






// GET A LIST OF ALL THE DATA BASES ON THIS CONNECTION
// MAN PAGE: http://php.net/manual/en/function.mysql-list-dbs.php
if (!$db_list = mysql_list_dbs($dbcx))
{
   $errmsg = mysql_errno() . ' ' . mysql_error();
   echo "<br/>NO DB LIST: ";
   echo "<br/> $errmsg <br/>";
   die();
}
// MAN PAGE: http://php.net/manual/en/function.mysql-fetch-object.php
while ($row = mysql_fetch_object($db_list))
{
    $db_names[] = $row->Database ;
}
echo "<br/>LIST OF DB NAMES: ";
var_dump($db_names);

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