Open an SQL connection just once - mysqli_query - php

Question

I used
mysqli_connect("infos in here");
at the top of my page, and tried to use
mysqli_query("INSERT INTO and other info here");
When I do that, I get this error:
Warning: mysqli_query() expects at least 2 parameters, 1 given in (...)
But if I instead use
$con = mysqli_connect("infos in here");,
$mysqli_query($con,"INSERT INTO and other info here");
The error goes away, and my script works.
My problem is that I need to use mysqli_query two different times in my page, and I don't want to open the connection again when it's already open.
How can I handle this?
Thanks.

Answer 1

My problem is that I need to use mysqli_query two different times in
my page, and I don't want to open the connection again when it's
already open.
How is it a problem ? open once query as many times then close the connection, example:
<?php
$con=mysqli_connect("localhost","my_user","my_password","my_db");
// Check connection
if (mysqli_connect_errno()){
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
// Perform queries
mysqli_query($con,"SELECT * FROM Persons");
//one more
mysqli_query($con,"INSERT INTO Persons (FirstName,LastName,Age)
VALUES ('Glenn','Quagmire',33)");
mysqli_close($con);
?>

Answer 2

No need to connect two times. An example here..
$con = mysqli_connect("host", "user", "password", "db");
if(mysqli_connect_errno()){
die(mysqli_connect_error());
}
//Query one
$result1 = mysqli_query($con, 'Query String');
//Query Two
$result2 = mysqli_query($con, 'Query String'); //Used same $con variable
//After finishing all queries
mysqli_close($con);
If you need to select multiple database then
$con = mysqli_connect("host", "user", "password");
//for DB bd_name1
mysqli_select_db($con, 'bd_name1');
$result1 = mysqli_query($con, 'Query String');
//for DB bd_name2
mysqli_select_db($con, 'bd_name2');
$result2 = mysqli_query($con, 'Query String');
But not connect frequent time.