Constructed rows

You can use a constructed row to specify an expression as a field value for a row variable. The constructed expression must use a row constructor and evaluate to a data type that is compatible with the field type of the field.

Suppose you have a nested-row variable that is declared as follows: 
EXEC SQL BEGIN DECLARE SECTION;
   row (fld1 integer, fld2 row(x smallint, y char(5))) a_nested_row;
EXEC SQL END DECLARE SECTION;
The following UPDATE statement uses the ROW constructor to specify expressions in the value for the fld2 field of the a_nested_row variable: 
EXEC SQL update table(:a_nested_row) 
   set fld2 = row(:an_int, a_func(:a_strng));

For more information about the syntax of a row constructor, see the Expression segment in the Informix® Guide to SQL: Syntax.