public function where(string $where): QueryBuilder
    {
        if (empty($this->where)) {
            $this->setWhere($where);

            return $this;
        }

        $this->setWhere($where, Statement::WHERE_AND);

        return $this;
    }
public function where(string $where): QueryBuilder
    {
        if (empty($this->where)) {
            $this->setWhere($where);

            return $this;
        }

        $this->setWhere($where, Statement::WHERE_AND);

        return $this;
    }
public function where ( string $ where ) : QueryBuilder { if ( empty ( $ this -> where ) ) { $ this -> setWhere ( $ where ) ; return $ this ; } $ this -> setWhere ( $ where , Statement :: WHERE_AND ) ; return $ this ; }
Add a where condition to the query statement.
- Each additional use will add an `AND` where condition.

<code>
$queryBuilder
->select()
->table('table')
->where('column = :column');

$queryBuilder
->select()
->table('table')
->where('column = :column')
->where('column2 = :column2');
</code>

@param string $where

@return static
Add a where condition to the query statement . - Each additional use will add an AND where condition .