Working a PHP function into a SQL statement

[tomandhannah]

I just posted this in General Help, and then realized it probably should have been here... Sorry.

I currently have the following code in a program I'm working on:

$table_name = "articles";
$r_fields = "SELECT id, title, body, imagedesc, teaser, imagedesc,";

$sql = "$r_fields \n"
	.boolean_sql_select(
		boolean_inclusive_atoms($q),
		$fulltext_key)." as relevance \n"
	."FROM $table_name \n"
	."WHERE \n"
	.boolean_sql_where($q,$fulltext_key)." \n"
	."HAVING relevance>0 \n"
	."ORDER BY relevance DESC \n"
	."$limit \n";

The above code (along with some other include files and variables) works as expected, generating a MySQL query. However, what I really need is for $table_name and $r_fields to be dynamic.

So, I worte the following two functions:

function selectedfields($rfields) {
$nofields = count($rfields);
IF ($nofields == "1") {
foreach ($rfields as $value) {
echo "SELECT $value"; }
}
ELSE {
print "SELECT ";
foreach ($rfields as $value) {
echo "$value, "; }
}
}

function tablename($tables) {
$nofields = count($tables);
IF ($nofields == "1") {
foreach ($tables as $value) {
echo "$value"; }
}
ELSE {
foreach ($tables as $value) {
echo "$value, "; }
}
}

These functions work as expected. The top one (selectedfields($rfields)) generates output identical to $r_fields. And the bottom one (tablename($tables)) generates output identical to $table_name.

So... how do I work these functions into the $sql statement? I've tried calling the functions directly within the $sql definition, but it's not working. For example, if I replace the line:
$sql = "$r_fields \n"
With:
$sql = selectedfields($rfields)." \n"

Then I get an error in my SQL syntax, eventhough the output of $sql looks right. What gives? Any ideas?

[tomhath]

Your functions should "return" a value, not "echo" it from inside the function.

http://www.phpbuilder.com/manual/functions.returning-values.php

But you don't need those functions anyway, just use php's built in "join" or "implode" functions

http://www.phpbuilder.com/manual/function.implode.php

[tomandhannah]

Actually.... I got it working just perfectly thanks to tomhath's suggestion to use implode()

I replaced the original $table_name = 'articles'; and $r_fields = (...); with

$table_name = implode(", ", $tables);
$r_fields = implode(", ", $rfields);

And it works like a charm. Such and easy fix, and much better than the lengthy functions I had.