MySQL error set

I encountered many problems when I used MySQL to write functions today. Now I will write down the problems and solutions.

1: in MySQL, a semicolon (-) is required for each row ,--!

Second, the result set cannot be returned in MySQL functions. therefore, select * From tablename and select column_name from tablename cannot be used. otherwise, the error not allowed to return aresult set from a function is reported. change the select XX into method ..

Third: error message :"This function has none of deterministic, no SQL, or reads SQL data in its declaration and binary"

we should have enabled bin-log, we must specify whether our function is
1 uncertain deterministic
2 No SQL statement, of course, the data will not be modified.
3 reads SQL data only reads data, of course, the data will not be modified.
4 modifies SQL data
5 contains SQL statements

In the function, only deterministic, no SQL, and reads SQL data are supported. If bin-log is enabled, we must specify a parameter for our function.

we can disable this by setting the following parameters.

set global log_bin_trust_function_creators = 1;

Last completedCodeAs follows:

Code

  Create  Definer  =     CURRENT_USER     Function  'Func _ get_city_name '('cid'  Int  )
  Returns     Varchar  ( 50  )
  Begin  
  Declare  Result  Varchar  (  50  );
  Set  Result  =     ''  ;
  Select Region_name  Into  Result  From  Vsvt_region  Where  Region_id  =  CID;
  Return  Result;
  End  ;;