ansinull determines whether NULL-valued operands in aggregate functions are evaluated in compliance with the ANSI SQL standard. If you use set ansinull on, the SAP ASE server generates a warning when an aggregate function eliminates a null-valued operand from the calculation.
select avg (total_sales) from titles
----------- 6090
However, if you perform the same query with set ansinull on, the SAP ASE server returns the following:
1> use pubs2 2> go 1> select avg (total_sales) from titles 2> go
----------- 6090 (1 row affected)
1> set ansinull on 2> go 1> select avg (total_sales) from titles 2> go
----------- 6090 Warning - null value eliminated in set function (1 row affected)
This message indicates that some entries in total_sales contain NULL instead of a real amount, so you do not have complete data on total sales for all books in this table. However, of the available data, the value returned is the highest.