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 ( amount_of_transaction INTEGER, transaction_type_code VARCHAR, share_count VARCHAR )

### Question ###
Show the minimum amount of transactions whose type code is 'PUR' and whose share count is bigger than 50.

### Accurate SQL ###

SELECT MIN(amount_of_transaction) FROM TRANSACTIONS WHERE transaction_type_code = "PUR" AND share_count > 50