Zend Framework queries encountered little doubt, thank God

Zend Framework query a little bit of a problem, thank you, great gods!
$tableUsers _1 = engine_api::_ ()->getdbtable (' Users ', ' user ');
$select _companies = $tableUsers _1->select ();
$select _companies->where ('. $table->info (' name '). ' '. ' level_id ' =? ', 6);

This is the query satisfies the level_id=6 condition, then I think the query satisfies both level_id=6 and satisfies the enabled=1, the query statement how to write, these two conditions are in this one table. There is also where ("'. ' $table ' what does that mean!
------Solution--------------------
$select _companies->where ('. $table->info (' name '). ' '. ' level_id ' =? and ' enabled ' = 1 ', 6);

Where ("'. '. $table ' is a string concatenation, ' is used to turn the name of the table, the field name, because if your table name is index (index is the SQL key), the direct write select * from index will be wrong, you need to write a select * from" in Dex '

