Union Limit Method

The union_limit method is part of Query Builder for limiting query result by executing LIMIT [A],[B] SQL command. This method also suitable for creating pagination with datatables pagination.

Basic Usage

Here is the basic usage union_limit method from $db property on SENE_Model class.

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$this->db->union_limit(int $a, int $b): $this->db

Parameters

This method has 2 required parameters.

$a

The $a value can be zero or positive integer for specifying the offset of the first row to be returned.

$b

The $b value can be zero or positive integer for specifying the maximum number of rows to be returned.

Example

On this example will show limiting the result query by using union_limit method in a model class.

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<?php
class Blog_Model extends SENE_Model{
  var $tbl = 'd_blog';
  var $tbl_as = 'b';

  public function __construct(){
    parent::__construct();
    $this->db->from($this->tbl,$this->tbl_as);
  }
  public function searchByScore($keyword){
    $this->db->union_flush();

    //1st union
    $this->db->select('id');
    $this->db->select('title');
    $this->db->select('excerpt');
    $this->db->select('date_modified');
    $this->db->select_as("3",'score');
    $this->db->from($this->tbl,$this->tbl_as);
    $this->db->where('title',$keyword,'or','like',1,0);
    $this->db->where('excerpt',$keyword,'or','like',0,1);
    $this->db->union_create();

    //2nd union
    $this->db->select('id');
    $this->db->select('title');
    $this->db->select('excerpt');
    $this->db->select('date_modified');
    $this->db->select_as("2",'score');
    $this->db->from($this->tbl,$this->tbl_as);
    $this->db->where('title',$keyword,'or','like%',1,0);
    $this->db->where('excerpt',$keyword,'or','like%',0,1);
    $this->db->union_create();

    //2nd union
    $this->db->select('id');
    $this->db->select('title');
    $this->db->select('excerpt');
    $this->db->select('date_modified');
    $this->db->select_as("1",'score');
    $this->db->from($this->tbl,$this->tbl_as);
    $this->db->where('title',$keyword,'or','%like',1,0);
    $this->db->where('excerpt',$keyword,'or','%like',0,1);
    $this->db->union_create();

    //3nd union
    $this->db->select('id');
    $this->db->select('title');
    $this->db->select('excerpt');
    $this->db->select('date_modified');
    $this->db->select_as("0",'score');
    $this->db->from($this->tbl,$this->tbl_as);
    $this->db->where('title',$keyword,'or','%like%',1,0);
    $this->db->where('excerpt',$keyword,'or','%like%',0,1);
    $this->db->union_create();

    $this->db->union_select('id,title,date_modified,score','score');
    $this->db->union_group_by('id');
    $this->db->union_order_by('score','desc')->union_limit(1, 14);
    return $this->db->union_get();
  }
}