I want to save data in a mysql table database using drupal 7 (costume module), but my question is that depends if the value exists I have to use the UPDATE command and if not INSERT command but I don't know how to write this code with the db api.
In the general sense, a Merge query is a combination of an Insert query and an Update query. If a given condition is met, such as a row with a given primary key already existing, then an Update query is run. If not, an Insert query is run.
Thus, db_merge adds it, if it doesn't exist yet. OR updates it, if it already exists.
db_merge('example') ->key(array('name' => $name)) ->fields(array( 'field1' => $value1, 'field2' => $value2, )) ->execute();
by: dzutaro, tlyngej, stewart.adam, AndreyMaximov