Insert command failing [duplicate] - php

Question

This question already has an answer here:
Syntax error due to using a reserved word as a table or column name in MySQL
(1 answer)
Closed 5 years ago.
So, I'm having trouble getting data into this table. I have a similar table setup for memberships. If I change the insert into query to membership from join everything works perfectly, but as soon as I change the table to join it stops working. The table seems to be properly setup since it's basically the same as my membership table, but for some reason data will not insert. I can't think of what could be causing my problem so I'm coming to the experts.
Note that this code all works perfectly when going into a different table. Thanks in advance.
if ( isset($_POST['btn-join']) ) {
// clean user inputs to prevent sql injections
$groupID = trim($_POST['groupID']);
$groupID = strip_tags($groupID);
$groupID = htmlspecialchars($groupID);
$teamname = trim($_POST['teamname']);
$teamname = strip_tags($teamname);
$teamname = htmlspecialchars($teamname);
// Query groups to set group name
$query2 = "SELECT groupName FROM groups WHERE groupID='$groupID'";
$result2 = mysqli_query($con,$query2);
$groupquery = mysqli_fetch_array($result2,MYSQLI_ASSOC);
$groupname = $groupquery['groupName'];
// groupID validation
if (empty($groupID)) {
$error = true;
$groupIDError = "Please enter valid Group ID.";
} else {
// check email exist or not
$query3 = "SELECT groupID FROM groups WHERE groupID='$groupID'";
$result3 = mysqli_query($con,$query3);
$count = mysqli_num_rows($result3);
if($count!=1){
$error = true;
$groupIDError = "Provided Group does not exist.";
}
}
// basic teamname validation
if (empty($teamname)) {
$error = true;
$nameError = "Please enter your Team Name.";
} else if (strlen($teamname) < 3) {
$error = true;
$nameError = "Team Name must have at least 3 characters.";
}
// if there's no error, continue to signup
if( !$error ) {
$query = "INSERT INTO join(groupID,userID,groupName,teamName) VALUES('$groupID','$userID','$groupname','$teamname')";
$membership = mysqli_query($con,$query);
if ($membership) {
$errTyp = "success";
$errMSG = "Account successfully updated";
header("Location: dashboard.php");
} else {
$errTyp = "danger";
$errMSG = "Something went wrong, try again later...";
}
}
}
SQL:
CREATE TABLE IF NOT EXISTS `join` (
`jID` int(11) NOT NULL AUTO_INCREMENT,
`groupID` varchar(32) NOT NULL,
`userID` varchar(32) NOT NULL,
`groupName` varchar(35) NOT NULL,
`teamName` varchar(32) NOT NULL,
`joinDate` datetime DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`jID`),
UNIQUE KEY `groupID` (`groupID`,`userID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1;

Answer 1

join is a reserved word in SQL. To avoid these sorts of issues, use backticks around table and column names:
$query = "INSERT INTO `join`(`groupID`,`userID`,`groupName`,`teamName`) VALUES('$groupID','$userID','$groupname','$teamname')";
$membership = mysqli_query($con,$query);
As a side note, you should really rewrite this query to use a prepared statement and then bind the variables to it. This is a SQL injection waiting to happen.