weiwei fang wrote:

Now I have a question about getting data from mysql database in rlm_wimax. I want to add some new attribute (such as the level of a single client) in the clients table of mysql. Then when a client request arrives to the freeradius server, the rlm_wimax can query the mysql to return the client's "new" attribute (newly defined by me, mentioned above) in the table back to the client. So if I can write the code in rlm_wimax.c by invoking the functions defined in rlm_sql/rlm_mysql, or I need to write my own drive code to access the mysql database?

Nope. See "man unlang", "Obtaining results from databases" Reply-Message := "%{sql:SELECT .....}" Alan DeKok.