Informix - Returning Information as Result Set (Dummy Tables)
In Informix, you have to specify the FROM clause in SELECT statements. In order to return the value from a function, expression as a single row result set, you can use SELECT … FROM systables WHERE tabid=1 that is guaranteed to return 1 row.
SELECT CURRENT FROM systables WHERE tabid=1;
This query returns the current date and time as a result set.
Dummy Tables - Differences between Informix and other Databases
|Database||Returning Result Sets|
|Oracle||SELECT … FROM dual|
|SQL Server||SQL Server SELECT - SELECT without FROM is allowed (no dummy tables required)|