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_name_93 (category VARCHAR, year VARCHAR, competition VARCHAR)

### Question ###
What are the categories of events that occurred after 2007 that were World Championships?

### Accurate SQL ###

SELECT category FROM table_name_93 WHERE year > 2007 AND competition = "world championships"