我正在从注册表中收集数据，其中一个字段是外键。外键是（tru id），这是我正在使用的代码。这里的问题是我得到了由tru id引起的一般错误。
这是我的表的架构：

CREATE TABLE kfupm_tournament (
        tr_id numeric NOT NULL,
        tr_name character varying(40) NOT NULL,
        start_date date NOT NULL,
        end_date date NOT NULL,
    PRIMARY KEY (tr_id) );
    CREATE TABLE kfupm_team (
        team_id numeric NOT NULL,
        tr_id numeric NOT NULL,
        team_group character(1) NOT NULL,
    PRIMARY KEY (team_id, tr_id),
FOREIGN KEY (tr_id) REFERENCES kfupm_tournament (tr_id));

我想问题是因为我正在插入tru id，因为它是本地密钥。

<?php
        $conn = mysqli_connect("localhost", "root", "", "ICS324");
        // Check connection
        if($conn === false){
            die("ERROR: Could not connect. " 
                . mysqli_connect_error());
        }
        $tr_id = $_REQUEST['tr_id'];
        $team_id = $_REQUEST['team_id'];
        $team_group = $_REQUEST['team_group'];
       // here is the problem
        $sql = "INSERT INTO kfupm_team VALUES ('$tr_id', 
            '$team_id','$team_group')" ;
        if(mysqli_query($conn, $sql)){
            echo "<h3>data stored in a database successfully." 
                . " Please browse your localhost php my admin" 
                . " to view the updated data</h3>"; 
            echo nl2br("\n$tr_id\n $tr_name\n "
                . "$start_date\n $end_date");
        } 
        ?>