jpa - methode JEE implementation -

i implemented method allows me generate test ( entire of question ) automatically problem : method take number of random questions category of questions generated (i have entié category , therefore table too) don't know put category in query. , secondly random() not taked jpql can ?

schema of database

public list<question> preparerandomtest(int number_of_questions, categorie      categorie){        string jpql = "select q question q order random() limit "+number_of_questions  ;      query query = entitymanager.createquery(jpql);       return query.getresultlist();     } 

you trying use java persistence query language here, hence solution not taking random account. use native query , build query native sql string, native query plain sql statement without entity object reference (like question). way normal sql keywords random etc read.

native query tutorial

instead of using

string jpql = "select q question q order random() limit "+number_of_questions  ; 

use:

"select * question category="+category+" order random() limit "+number_of_questions; 

additional advice: category string "enum" in code match string value in database category column.