This warning is rising because as the default MySQL server supports replication. This means that BINARY LOGGING is turned ON.
So, there is a replication log that contains all the changes that is made to the database.
Unfortunately, MySQL is not checking the statements that are stored in the SPs or UDFs. The server can't say, whether the procedure changes the data in the database or not.
That is why MySQL server asks for the explicit specification of the operations that are performed inside the SP or UDF, if the binary logging is on.
This doesn't mean that the procedure will be prohibited to execute the update statements if it is defined as DETERMINISTIC or READS SQL DATA or NO SQL. The characteristics are advisory only.
So, If you are not replicating your server and the binary logging is on as the default, just turn it off to not receive the warning.
Or, if you are replicating the server then you can:
1. Set the SUPER privileges for your user;
2. Change the system variable for the server like:
mysql> SET GLOBAL log_bin_trust_function_creators = 1 ;
3. Set this variable by using the --log-bin-trust-function-creators=1 option when starting the server.