framework/db/Query.php
public function innerJoin($table, $on = '', $params = [])
    {
        $this->join[] = ['INNER JOIN', $table, $on];
        return $this->addParams($params);
    }
public function innerJoin($table, $on = '', $params = [])
    {
        $this->join[] = ['INNER JOIN', $table, $on];
        return $this->addParams($params);
    }
Appends an INNER JOIN part to the query.
@param string|array $table the table to be joined.

Use a string to represent the name of the table to be joined.
The table name can contain a schema prefix (e.g. 'public.user') and/or table alias (e.g. 'user u').
The method will automatically quote the table name unless it contains some parenthesis
(which means the table is given as a sub-query or DB expression).

Use an array to represent joining with a sub-query. The array must contain only one element.
The value must be a [[Query]] object representing the sub-query while the corresponding key
represents the alias for the sub-query.

@param string|array $on the join condition that should appear in the ON part.
Please refer to [[join()]] on how to specify this parameter.
@param array $params the parameters (name => value) to be bound to the query.
@return $this the query object itself