php - pdo fails to insert data into database?

Question

Error code:

SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'insert into admin (userid,password,collection) values ('John', 'Doe', 'jo')' at line 1

pdo code:

$servername="localhost";
$user="root";
$psw="444444";
try{
            
            
            $con=new PDO("mysql:host=$servername;dbname:mydb",$user,$psw);
            $con->query("set names utf8");
            $con->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

            
            if($con){
                
                $sql="use mydb insert into admin (userid,password,collection) values ('John', 'Doe', 'jo')";
                $con->exec($sql);

            }
            }
            catch(PDOException $e)
            {
                echo  $e->getMessage();
            }

The error message says that my sql has a syntax error, but my sql statement can insert data when mysql is executed, and I have the insert permission. Why is there an error here?

Answer 1

use mydbAdd a semicolon after it, because these are two sentences of sql

Answer 2

You have already specified the database when connecting, so there is no needuse mydb.

Answer 3

Is it because the symbols are not used well? Try this:
$sql='use mydb insert into admin ("userid","password","collection") values ​​("John", "Doe", "jo" )';

Answer 4

use mydb does not need to be specified every time, just specify it once, and then SQL