HiRDB database supports AVG function without OVER clause. SQLWays leaves it as is.

Oracle:

n:= AVG(DISTINCT a); 

HiRDB:

SET n= AVG(DISTINCT a); 

HiRDB hasn't equivalents for AVG function with OVER clause. SQLWays leaves it as is and adds message /* SQLWays: Could not convert 'AVG' */.

Oracle:

n:= AVG(a) OVER(partition by b); 

HiRDB:

SET n= AVG(a) OVER(partition by b); 
/*Сould not convert 'AVG'*/

References in Wiki