building dynamic sql statements in php

[shreyas]

Hi i am new to php and i want to make my sql statements dynamic but i am not getting what is want.
$query1 = "SELECT date_temp, AVG(air_temp_c) FROM sample where date_temp = '$a'";
$result1 = mysql_query($query1);
while($row = mysql_fetch_array($result1))
{
$date = $row['date_temp'];
$air = $row['AVG(air_temp_c)'];
if($counter<$u && $air>-1)
{
echo "<tr>";
echo "<td>" . $date . "</td>";
echo "<td>" . $air . "</td>";
echo "</tr>";
$dataSet->addPoint(new Point("$date", $air));
$counter++;
}

							}

now instead of air_temp_c in AVG(air_temp_c) i want to replace it with a variable which i take from the user. how can i do this?

[shreyas]

i have value in the variable say $input='air_temp_c' tried to replace it with AVG($input) or AVG('$input') or AVG('.$input') but nothing works and i get error message as
Notice: Undefined index: AVG(air_temp_c) in C:\wamp\www\work\second_php_work\avg_date.php on line 148

[bradgrafelman]

Can you show us the same code snippet again after you attempted to make the changes you're describing?

[shreyas]

$query1 = "SELECT date_temp, AVG('.$takeinput.') FROM sample where date_temp = '$a'";
$result1 = mysql_query($query1);
while($row = mysql_fetch_array($result1))
{
$date = $row['date_temp'];
$air = $row['AVG('.$takeinput.')'];
if($counter<$u && $air>-1)
{
echo "<tr>";
echo "<td>" . $date . "</td>";
echo "<td>" . $air . "</td>";
echo "</tr>";
$dataSet->addPoint(new Point("$date", $air));
$counter++;
}

							}

this is the code snippet after mking changes...stilll same index problem...this dynamic variable assigning works well with query like "select * from sample where date='$d'" but fails with when i try to use with sql function like COUNT() or AVG()..