The FOR UPDATE OF clause identifies the columns that can be updated in a later positioned UPDATE statement. It restricts the table columns that can be updated to those specified in the column-name list. These column names must be defined for the table or view appearing in the first FROM clause of the fullselect, and must not be qualified. FOR UPDATE OF cannot be used if the result table is read-only, nor can it be used in a statement containing a FOR FETCH ONLY clause.
Syntax
The FOR UPDATE OF clause format appears below:
FOR UPDATE OF column-name[,...]
where: