The code example from this page shows how to make a MySQL SELECT with JOIN table of different database, using PDO.
The trick is to specify both the database name and table in the SQL query, by using the syntax: database_name.table_name.
- This method works if you use an user and password for connecting to MySQL that has access to both databases.

Complete code example

// Data for connecting to MySQL
$mysql =['host'=>'localhost', 'dbname'=>'db_1', 'user'=>'root', 'pass'=>'password'];

//connects with PDO 
try {
  $conn = new PDO('mysql:host='. $mysql['host'] .'; dbname='. $mysql['dbname'], $mysql['user'], $mysql['pass']);
  $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); //set the PDO error mode to exception
}
catch(PDOException $e){ exit('Connection failed: '. $e->getMessage());}

$sql ="SELECT t1.id, t1.name, t2.col_db2 FROM db_1.table1 AS t1
 LEFT JOIN db_2.table2 AS t2 ON t1.id = t2.id";
$stmt = $conn->query($sql);

if($stmt !== false) {
  //shows selected data
  foreach($stmt as $row) {
    echo $row['id'] .'--'. $row['name'] .'--'. $row['col_db2'] .'<br>';
  }
}
else {
  echo '0 results';
}
- In this way you can join multiple tables from different databases.

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Click on the HTML tag which creates an horizontal line in web page.
<br /> <em> <hr />
Some content ...
<hr />
Content under line ...
Which CSS property defines the text color?
font-style font-variant color
h2 {
  color: #cbdafb;
}
Click on the function which searches if a character, or text exists in a string.
indexOf() toString() split()
var str = "Web courses - http://CoursesWeb.net/";
if(str.indexOf("http://") == -1) alert("http:// isn`t in string");
else alert("http:// is in string");
Which function splits a string into an array of strings based on a separator?
array_merge() explode() implode()
$str = "apple,banana,melon,pear";
$arr = explode(",", $str);
var_export($arr);      // array (0=>"apple", 1=>"banana", 2=>"melon", 3=>"pear")
Mysql SELECT JOIN tables on two different Databases

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