$nome=$_POST['nome'];
$sobrenome=$_POST['sobrenome'];
$email=$_POST['email'];
$senha=$_POST['senha'];
$sql = mysqli_query("INSERT INTO usuarios (nome, sobrenome, email, senha)
VALUES ('$nome', '$sobrenome', '$email', '$senha')");
The error you are giving: Warning: mysqli_query() expects at least 2 parameters, 1 given in /home/u158302715/public_html/bemvindo.php on line 40
The first parameter has to be the MySQL connection you are opening with mysqli_connect() . For you to use only the query you would have to use the static mode of the function with mysqli::query() .
Take a look at the documentation for this function in php.net: link
Now look at the code example here in W3Schools: link
Note the line:
$con=mysqli_connect("localhost","my_user","my_password","my_db");
And now you see that $con is passed as a parameter:
mysqli_query($con,"SELECT * FROM Persons");
and simple in your code is so $sql = mysqli_query("INSERT INTO usuarios (nome, sobrenome, email, senha) VALUES ('$nome', '$sobrenome', '$email', '$senha')"); change so
$sql = mysqli_query($variavel de conexao, "INSERT INTO usuarios (nome, sobrenome, email, senha) VALUES ('$nome', '$sobrenome', '$email', '$senha')");
You are using mysqli and the form of writing is as it was written in mysql , so whenever you have a query of mysqli you always have to pass conexao to it '