Laravel's database query builder provides a convenient, fluent interface to creating and running database queries.
- It uses PDO parameter binding to protect your application against SQL injection. There is no need to clean strings passed as bindings.


To perform a basic "inner join", you may use the join() method on a query builder instance.
The first argument is the name of the table you need to join to; the remaining arguments specify the relation of the columns for the join.
- You can join to multiple tables in a single query:
$users = DB::table('users')
 ->join('contacts', '', '=', 'contacts.user_id')
 ->join('orders', '', '=', 'orders.user_id')
 ->select('users.*', '', 'orders.price')
- To perform a "left join" query, use the leftJoin() method, in the same way as the join() method.
$users = DB::table('users')
 ->leftJoin('posts', '', '=', 'posts.user_id')


To "union" two queries together, create an initial query and use the union() method to union it with a second query.
$first = DB::table('users')->whereNull('first_name');

$users = DB::table('users')->whereNull('last_name')

- Documentation: Laravel - Database: Query Builder

Daily Test with Code Example

Which HTML5 tag can be used to embed an external application (SWF, PDF) in web page?
<mark> <embed> <canvas>
<embed src="flash_game.swf" width="450" height="350" />
Which CSS pseudo-element adds a special style to the first line of a text?
:first-letter :before :first-line
#id:first-line {
  font-weight: bold;
  color: blue;
Click on the window object property which gets or sets the URL of current page.
window.location window.self window.status
var url = window.location;
Indicate the PHP function used to get the contents of a file or page and store it into a string.
fopen() file_put_contents() file_get_contents()
$homepage = file_get_contents("");
echo $homepage;
MySQL Database, Query Builder: Join and Union

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