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 TRANSACTIONS ( transaction_type_code VARCHAR )

### Question ###
Show the transaction type code that occurs the most frequently.

### Accurate SQL ###

SELECT transaction_type_code FROM TRANSACTIONS GROUP BY transaction_type_code ORDER BY COUNT(*) DESC LIMIT 1