PHP - Would You Please Comment/review/provide Feedback On Aptugo?

CREATE TABLE posts (
postId INT(11) NOT NULL UNIQUE AUTO_INCREMENT,	
title VARCHAR(255) NOT NULL,
author VARCHAR(24) NOT NULL,	
description TEXT NOT NULL,       
createdAt TIMESTAMP,
PRIMARY KEY (postId)    
);
CREATE TABLE comments(
commentId INT(11) NOT NULL UNIQUE AUTO_INCREMENT,    
comment  TEXT NOT NULL,
postId INT(11),
userId INT(11),
createdAt TIMESTAMP,	
PRIMARY KEY (commentId),
FOREIGN KEY (userId) REFERENCES users(userId),
FOREIGN KEY (postId) REFERENCES posts(postId)   
);
CREATE TABLE replies (
repId INT(11) NOT NULL UNIQUE AUTO_INCREMENT,   
reply  TEXT NOT NULL,
userId INT(11),
commentId INT(11), 	
createdAt TIMESTAMP,     
PRIMARY KEY (repId),
FOREIGN KEY (userId) REFERENCES users(userId),
FOREIGN KEY (commentId) REFERENCES comments(commentId)     
);
CREATE TABLE users (
userId INT(11) NOT NULL UNIQUE AUTO_INCREMENT,
userName VARCHAR(100) NOT NULL,,	          
email VARCHAR(100) NOT NULL,
PRIMARY KEY (userId)
);

how to retrive userName,comment, and createdAt from users and comments table while I have used userId as a  Foreign key on the comment table

if it isn't correct, correct me please

Php Buddies,

Line 67:

$query = "SELECT page_url,link_anchor_text,page_description,keyphrases,keywords FROM links WHERE $_SESSION['search_column'] = ?";

I get error for the above:

Parse error: syntax error, unexpected '' (T_ENCAPSED_AND_WHITESPACE), expecting '-' or identifier (T_STRING) or variable (T_VARIABLE) or number (T_NUM_STRING) in C:\xampp\htdocs\test\select.php on line 67

How to fix this ?

Context:

	<?php
//include('error_reporting.php');
ini_set('error_reporting','E_ALL');//Same as: error_reporting(E_ALL);
ini_set('display_errors','1');
ini_set('display_startup_errors','1');
require('conn.php');
?>
	<form name = "search" method = "POST" action="<?php echo $_SERVER['PHP_SELF']; ?>">
<label for="keywords">Keywords:*</label>
<input type="text" name="keywords" id="keywords" placeholder="Input Keywords" required>
<br>
<label for="search_column">Search in ... ?</label>
<select name="search_column" id="search_column">
<option value="page_url">Page Url</option>
<option value="link_anchor_text">Link Anchor Text</option>
<option value="page_description">Page Description</option>
<option value="keyphrase">Keyphrase</option>
<option value="keywords">Keywords</option>
</select>
<br>
<label for="tos_agreement">Agree to TOS or not ? *</label>
<select name="tos_agreement" id="tos_agreement" required>
<option value="Yes">Yes</option>
<option value="No">No</option>
</select>
<br>
<input type="button" name="search_links" id="search_links" value="Search Links!">
<br>
<input type="reset">
<br>
</form>
	<?php
	if($_SERVER['REQUEST_METHOD'] === 'POST')
{
    if(ISSET($_POST['search_links']))
    {
        if(ISSET($_POST['page_url']))
        {
            $_SESSION['search_column'] = $_POST['page_url'];
        }
        elseif(ISSET($_POST['link_anchor_text']))
        {
            $_SESSION['search_column'] = $_POST['link_anchor_text'];
        }
        elseif(ISSET($_POST['page_description']))
        {
            $_SESSION['search_column'] = $_POST['page_description'];
        }
        elseif(ISSET($_POST['keyphrase']))
        {
            $_SESSION['search_column'] = $_POST['keyphrase'];
        }
        elseif(ISSET($_POST['keywords']))
        {
            $_SESSION['search_column'] = $_POST['keywords'];
        }
        
        //Re-write the following 4 lines ...
        mysqli_report(MYSQLI_REPORT_ALL|MYSQLI_REPORT_STRICT);
        mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
       $conn->set_charset('utf8mb4'); //Always set Charset.
	        $query = "SELECT page_url,link_anchor_text,page_description,keyphrases,keywords FROM links WHERE $_SESSION['search_column'] = ?";
	        $stmt = mysqli_stmt_init($conn);
	        if(mysqli_stmt_prepare($stmt,$query))
        {
            mysqli_stmt_bind_param($stmt,'s',$_SESSION['search_column']);
            
            $result = mysqli_stmt_bind_result($stmt,$page_url,$link_anchor_text,$page_description,$keyphrase,$keywords);
            mysqli_stmt_execute($stmt);
            
            mysqli_stmt_fetch($stmt);
            
            while(mysqli_stmt_fetch($stmt))
            {
                echo "url"; echo "<br>";
                echo "anchor_text"; echo "<br>";
                echo "description"; echo "<br>";
                echo "keyphrases"; echo "<br>";
                echo "keywords"; echo "<br>";
                echo "|";
                echo "<br>";
            }
            
            mysqli_stmt_close($stmt);
            mysqli_close($conn);
        }
        else
        {
            echo "1. QUERY failed!";
        }
	        if(mysqli_stmt_prepare($stmt,$query))
        {
            mysqli_stmt_bind_param($stmt,'sssss',$_POST['page_url'],$_POST['link_anchor_text'],$_POST['page_description'],$_POST['keyphrases'],$_POST['keywords']);
            mysqli_stmt_execute($stmt);
            
            $result = mysqli_stmt_get_result($stmt);
            
            while($row = mysqli_fetch_array($result,mysqli_assoc))
            {
                $page_url = $row['page_url']; echo $page_url; echo "<br>";
                $link_anchor_text = $row['link_anchor_text']; echo $link_anchor_text; echo "<br>";
                $page_description = $row['page_description']; echo $page_description; echo "<br>";
                $keyphrases = $row['keyphrases']; echo $keyphrases; echo "<br>";
                $keywords = $row['keywords']; echo $keywords; echo "<br>";
                echo "|";
                echo "<br>";
            }
            
            mysqli_stmt_close($stmt);
            mysqli_close($conn);
        }
        else
        {
            die("2. QUERY failed!");
        }
    }
}
	
?>