Oracle locking with SELECT…FOR UPDATE OF

问题

I'm selecting from tables FOO and BAR. I'd like to lock the records of FOO which are being returned, but I don't want the records of BAR to be locked.

cursor c_foobar is 
select foo.*, bar.* from
foo, bar
where foo.id = bar.foo_id
for update of <what should I put here?>

It seems like I need to specify individual columns, but I want the entire record of foo to be locked. e.g. I wish I could do something like:

cursor c_foobar is
select foo.*, bar.* from
foo, bar
where foo.id = bar.foo_id
for update of foo

Do I have to enumerate every column of foo in the for update of section in order to lock them all? Or can I arbitrarily choose any column in foo, even those which are not its primary key, and it will lock the entire record?

回答1:

From the 10G PL/SQL documentation:

When querying multiple tables, you can use the FOR UPDATE clause to confine row locking to particular tables. Rows in a table are locked only if the FOR UPDATE OF clause refers to a column in that table. For example, the following query locks rows in the employees table but not in the departments table:

DECLARE
  CURSOR c1 IS SELECT last_name, department_name FROM employees, departments
    WHERE employees.department_id = departments.department_id 
          AND job_id = 'SA_MAN'
      FOR UPDATE OF salary;

来源：https://stackoverflow.com/questions/3070410/oracle-locking-with-select-for-update-of