php mysql select statement

Question

I am having difficulties with a MYSQl select statement. Is it possible to return a value where the right value's match. eg. I have a table.

id |   1   |   2   |   3   | etc. <--- COLUMNS
1  | Value | Value | Value | etc.
2  | Value | Value | etc.. 
3  | Value | Value |
4  | Value | Value |
5  | Value | Value | etc...

Im am trying through php to query the database to return value with.

$id = 3;
$inputvalues = "SELECT 'column'
FROM `DB`
WHERE `id` = $id
";

$return = mysql_query($inputvalues, $connection);


while ($r = mysql_fetch_array($return)){
$r[0]; 
echo "$loc = $row[3]<br />";

I think in theory this should work however all the returned value's come back empty?

Is this possible?

This should be possible, post your actual code and we may be able to help. Right now it's impossible to assist you. Also, presumably where you have DB you mean Table — Adam Casey
– Adam Casey, Commented Mar 22, 2011 at 1:09

Czechnology · Accepted Answer · 2011-03-22 01:10:06Z

2

You shouldn't use single quotes (') around the column names, you can use backticks (`).

SELECT column
FROM `DB`
WHERE `id` = '$id'

or

SELECT `column`
FROM `DB`
WHERE `id` = '$id'

Put together:

$id = 3;
$sql = "SELECT column
        FROM `DB`
        WHERE `id` = '$id'";

$return = mysql_query($inputvalues, $connection);

while ($r = mysql_fetch_array($return)) {
  print_r($r);
}

answered Mar 22, 2011 at 1:10

Czechnology

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5 Comments

GG. Over a year ago

Not need single quotes around an integer.

Czechnology Over a year ago

@ggregoire, quotes around numeric values are not required but it's a good practice to prevent some problems with (missing) input.

Christopher Over a year ago

Sorry I did'nt add in my code that the select column is actually a variable number. this could be my problem as inside the 'backticks' it may be trying to search the string of '$loc'.

zerkms Over a year ago

you can and should check about missed number. But quotes around number can cause some performance issues. Sometimes mysql is trying not to cast string numeric to plain number, but the numeric field itself to string.

Czechnology Over a year ago

@zerkms, of course one should check. It just feels somehow better not to put anything without quotes to the query (even though I usually use intval or floatval on numerics instead of escaping). But the main reason is that it's been recommended to me when I started with mysql (not sure if it was a book) but that doesn't mean it's (still) right. I'll take a closer look at it.

Jean-Philippe Leclerc · Accepted Answer · 2011-03-22 01:10:58Z

0

Have you tried your query in a DB editor like MySql Workbench?

Your query should look like the following:

 "SELECT column FROM DB WHERE id = '$id'"

You must surround the value with single quotes, not around the column name.

answered Mar 22, 2011 at 1:10

Jean-Philippe Leclerc

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Comments

MMT · Accepted Answer · 2011-03-22 04:59:05Z

0

If your columns are loaded dynamically don't use quotes around variable in php

$id = 3;
$sql = "SELECT {$column}
        FROM `DB`
        WHERE `id` = '$id'";

it seems like variable name isn't replaced with actual value in query

answered Mar 22, 2011 at 4:59

MMT

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