Cannot create a table with php and sql

Question

When I run this code with PHP it doesn't create a table.

$sqltablecreate = "CREATE TABLE userbase.'$username' ( ID int, category varchar(100), content varchar(1000), PRIMARY KEY (ID) )";
             if(mysqli_query($conn, $sqltablecreate)){
              echo "<script>alert('Table Created Successfully')</script>";
             } else {
              echo "<script>alert('Errors with Table creating')</script>";
             }