PHP, MYSQL noob joining(?) tables specifics - php

Question

I am new to PHP and am making a social network as practice and to apply what I have learned in the "real world". Anyhow, I have two tables in a MySQL database that i am trying to display on my site in the same html table that is being rendered through an php echo.
here are the tables
(table1)
note_system:
-id,
-username,
-note
(table2)
comments:
-id,
-cid (equals id from note_system),
-username,
-comment
so someone makes a post and it saves to the note_system table then someone comments on the post and it saves to the comment table with the id from the note_system table so a relation can be established.
So what I am trying to do is get the post comments to display with the relevant post. I have gathered that I need maybe a JOIN or UNION to make this happen but I am at a complete loss on how to do it. Been racking my brain and doing tons of google searches but I am not really getting anywhere. Everything I try gives me errors. The Notes display just fine and as intended but I can't for the life of me figure out how to get the comments to show up there too.
Here is my code (don't laugh at the noob-ness of my PHP, this is my 2nd PHP program ever and I obviously have much to learn, I would like to clean it up at some point but for now I just want it to be functional)
<?php
// Display Note_Wire
$con=mysqli_connect($host,$username,$password,$dbname);
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
//format and display the Note_Wire results with comments
$result = mysqli_query($con,"SELECT * FROM note_system");
while($row = mysqli_fetch_array($result))
{
echo "<center>";
echo "<table class='note_wire'>";
echo "<tr>";
echo "<td>" . $row['username'] . "</td>" ;
echo "</tr><tr>";
echo "<td><a href=''>vote up</a>" . " " . $row['rank'] . " " . "<a href=''>vote down</a></td>" ;
echo "</tr><tr>";
echo "<td> <a href='{$row['link']}' target='blank'>{$row['link']}</a>";
echo "</tr><tr>";
echo "<td>" . $row['note'] . "</td>" ;
echo "</tr> ";
//add comments attempt this is where I would like the comments to be displayed
echo '
<td><form action="add_comment.php" method="POST">
<input type="hidden" name="username" value="';
echo htmlentities($_SESSION['user']['username'], ENT_QUOTES, 'UTF-8');
echo '" />';
echo '<input type="hidden" name="cid" value="';
echo $row['id'];
echo '" />';
echo '<textarea name="comment">comment...</textarea></td></tr>
<tr><td><input type="submit" value="comment" />
</form></td></tr>
';
echo "</table>";
// break before next note-wire record renders
echo "<br />";
}
echo "</center>";
?>
I hope my chicken scratch programming makes sense. Thanks for your time and knowledge.

Answer 1

Really the comments are a different data set from the actual post you could just use a second query to get all of the comments related to the post. But table joins are very useful and you should learn them. In this case you would join the note_system and comments table on the shared ID (the foreign key).
So like so:
SELECT *
FROM note_system
LEFT JOIN comments ON comments.cid=note_system.id
This is a literal joining of the tables so your output will include all columsn from both tables as long as there is a match for the joining expression. If there isn't a CID column in the comments table that matches then the values for those columns will be NULL in your output. (If you wanted to only return rows where there is a match you could use an INNER join as opposed to the LEFT OUTER join I've used above.)
This is a good page explaining SQL table joins.

Answer 2

Heres the basics step for you if your a beginner in using php and mysql..
FIRST : SET UP CONFIGURATION FOR DATABASE USER,PASS,HOST,DBNAME
$conn = new mysqli('database_server','database_username','database_password','database_name');
SECOND : Create a Query(you may insert your query here)..
$result= $conn->query("SELECT SUM(Total_Steps) AS value_sum FROM users");
FINAL : SHOWN RECORDS USING MYSQL FUNCTIONS LIKE..
while($row = $result->fetch_assoc()){
echo $row['dabatase_columnname'];
echo $row['database_columnname'];
}
for your query try to use this one or either create a relative one.
SELECT 'enter column needed here with their specific database allias ex. TABLE1.ID'FROM NOTE_SYSTEM TABLE1 LEFT JOIN COMMENTS TABLE2 ON TABLE1.ID = TABLE2.CID;