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Check if column exists in mysql table with php

Posted on 2012-04-10
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Last Modified: 2012-04-10
Hi Experts!

As in title, I need a php script checking if column exists in table.

Thanks for any help.
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Question by:Zado
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6 Comments
 
LVL 34

Expert Comment

by:gr8gonzo
ID: 37828526
The "information_schema" table in MySQL is a special, internal table that holds all the information about the database structure. You can query it like this:

SELECT column_name FROM information_schema.columns WHERE table_name = 'my_table'

You can use that method / query to check for column existence.
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Author Comment

by:Zado
ID: 37828623
Thanks gr8gonzo, I wrote this:
$checkcolumn = mysql_query("SELECT $column FROM information_schema.columns WHERE table_name = '$tablename'");
if (mysql_num_rows($checkcolumn)>0) {echo "column does not exists!";} else {echo "column exists!";}

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but it doesn't work as expected, I keep trying...
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LVL 8

Author Comment

by:Zado
ID: 37828685
Ok, got it, it's probably not the best to do it, but it works, if you know better way, please let me know:

$tablename = $_GET['table'];
		$column = "UserID";
		
		$columnlist = array();
		$checkcolumn = mysql_query("SELECT column_name FROM information_schema.columns WHERE table_name = '$tablename'");
		while ($row = mysql_fetch_array($checkcolumn)) {
			$columnlist[] = $row['column_name'];
		}
		$columnlist = implode(',',$columnlist);
		if (strpos($columnlist,$column)!==false) {echo "column exists!";} else {echo "column does not exists!";}

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Author Comment

by:Zado
ID: 37828692
*up  'it's probably not the best way to do it'
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Accepted Solution

by:
gr8gonzo earned 500 total points
ID: 37828697
Sorry, try this:

$checkcolumn = mysql_query("SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='{$tablename}' AND COLUMN_NAME = '{$column}';");
if (mysql_num_rows($checkcolumn)>0) {echo "column does not exists!";} else {echo "column exists!";}

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LVL 8

Author Closing Comment

by:Zado
ID: 37828829
Thanks :-)
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