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 tag is used to add lists into <ul> and <ol> elements?
<dt> <dd> <li>
Which value of the "display" property creates a block box for the content and ads a bullet marker?
block list-item inline-block
.some_class {
  display: list-item;
Which instruction converts a JavaScript object into a JSON string.
JSON.parse() JSON.stringify eval()
var obj = {
 "courses": ["php", "javascript", "ajax"]
var jsonstr = JSON.stringify(obj);
alert(jsonstr);    // {"courses":["php","javascript","ajax"]}
Indicate the PHP class used to work with HTML and XML content in PHP.
stdClass PDO DOMDocument
$strhtml = '<body><div id="dv1"></div></body>';
$dochtml = new DOMDocument();
$elm = $dochtml->getElementById("dv1");
echo $elm->nodeValue;    //
MySQL Database, Query Builder: Join and Union

Last accessed pages

  1. AJAX Course, free Lessons (7411)
  2. AJAX and JSON (1019)
  3. Wake Up! (3449)
  4. Read Excel file data in PHP - PhpExcelReader (63706)
  5. JavaScript Course - Free lessons (15710)

Popular pages this month

  1. Contact page - CoursesWeb (1955)
  2. Tabs effect with CSS (1942)
  3. Insert, Select and Update NULL value in MySQL (1036)
  4. Read Excel file data in PHP - PhpExcelReader (832)
  5. PHP getElementById and getElementsByTagName (513)