Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_203_631 ( id number, "year" number, "name of show" text, "episodes" text, "other guests" text, "winner(s)" text )

### Question ###
how long has it been since chermaine sheh first appeared on a variety show ?

### Accurate SQL ###

SELECT present_ref - MIN("year") FROM table_203_631