An update cursor

An update cursor permits you to delete or update the current row; that is, the most recently fetched row. The following example in Informix® ESQL/C shows the declaration of an update cursor: 
EXEC SQL
   DECLARE names CURSOR FOR
      SELECT fname, lname, company
      FROM customer
   FOR UPDATE;
The program that uses this cursor can fetch rows in the usual way. 
EXEC SQL
   FETCH names INTO :FNAME, :LNAME, :COMPANY;
If the program then decides that the row needs to be changed, it can do so. 
if (strcmp(COMPANY, "SONY") ==0)
   {
   EXEC SQL
      UPDATE customer
         SET fname = 'Midori', lname = 'Tokugawa'
         WHERE CURRENT OF names; 
   }

The words CURRENT OF names take the place of the usual test expressions in the WHERE clause. In other respects, the UPDATE statement is the same as usual, even including the specification of the table name, which is implicit in the cursor name but still required.