在php中使用外键在表中插入值

Question

I am new to PHP and SQL. I simply want to register a user after a team of users has been created. Tables that i have used -

team

idTeam int(11) PK + AI
teamName varchar(25)

user

idUser int(11) PK + AI
name varchar(30)
username varchar(30)
password varchar(30)
team int(11) FK

I have used the following code-

<?php
session_start();
include('conn.php');

$name=$_POST['name'];
$team=$_POST['team'];
$username=$_POST['username'];
$password=$_POST['password'];

$qry="SELECT * FROM team WHERE idTeam='$team";

if(mysqli_query($con,$qry)){
  mysqli_query("INSERT INTO user(name, team, username, password)VALUES('$name', '$team', '$username', '$password')");

  header("location: add_user.php?remarks=success"); 
  mysqli_close($con);
}
else 
mysqli_error($con); 
?>

i used to get error- Mysql error 1452 - Cannot add or update a child row: a foreign key constraint failsMysql error 1452 - Cannot add or update a child row: a foreign key constraint fails

Example - I have pre-entered the contents of team table-

idTeam - teamName
  1      Arsenal
  2      Chelsea
  3      Liverpool

Now if i want to add a user then I would add him by entering in user table-

idUser   team   name   username  password
  1        2    abc    root      pass

So here i am unable to figure out what query should i use in PHP code?

Answer 1

There is a single quotation within your first sql query near idTeam='$team. idTeam is integer type. So it need not within single quotation. Make sure that you are passing value for $team variable that is exist in team table. Try following code.

$name=$_POST['name'];
$team=$_POST['team'];
$username=$_POST['username'];
$password=$_POST['password'];

$qry="SELECT * FROM team WHERE idTeam=$team";
$result = mysqli_query($qry);
$num_rows = mysqli_num_rows($result);
if($num_rows > 0){
    mysqli_query("INSERT INTO user(name, team, username, password)VALUES('$name', $team, '$username', '$password')");
}else{
    echo "Team is not valid!!!";
}
mysqli_close($con);
header("location: add_user.php?remarks=success");