Opening a Select Cursor
When you open either a Select cursor or an update cursor that is
created with the SELECT FOR UPDATE syntax, the SELECT statement
is passed to the database server with any values that are specified
in the USING clause. The database server processes the query to the
point of locating or constructing the first row of the active set.
The following example illustrates a simple OPEN statement in Informix®
ESQL/C:
EXEC SQL declare s_curs cursor for select * from orders;
EXEC SQL open s_curs;
An SPL routine cannot reference an update cursor in the OPEN statement.