ActiveRecord\AbstractRelationship::construct_inner_join_sql PHP Method

    public function construct_inner_join_sql(Table $from_table, $using_through = false, $alias = null)
    {
        if ($using_through) {
            $join_table = $from_table;
            $join_table_name = $from_table->get_fully_qualified_table_name();
            $from_table_name = Table::load($this->class_name)->get_fully_qualified_table_name();
        } else {
            $join_table = Table::load($this->class_name);
            $join_table_name = $join_table->get_fully_qualified_table_name();
            $from_table_name = $from_table->get_fully_qualified_table_name();
        }
        // need to flip the logic when the key is on the other table
        if ($this instanceof HasMany || $this instanceof HasOne) {
            $this->set_keys($from_table->class->getName());
            if ($using_through) {
                $foreign_key = $this->primary_key[0];
                $join_primary_key = $this->foreign_key[0];
            } else {
                $join_primary_key = $this->foreign_key[0];
                $foreign_key = $this->primary_key[0];
            }
        } else {
            $foreign_key = $this->foreign_key[0];
            $join_primary_key = $this->primary_key[0];
        }
        if (!is_null($alias)) {
            $aliased_join_table_name = $alias = $this->get_table()->conn->quote_name($alias);
            $alias .= ' ';
        } else {
            $aliased_join_table_name = $join_table_name;
        }
        return "INNER JOIN {$join_table_name} {$alias}ON({$from_table_name}.{$foreign_key} = {$aliased_join_table_name}.{$join_primary_key})";
    }