Oracle游标的查询

The initialization parameter OPEN_CURSORS in INITSID.ORA determines the maximum number of cursors per user.

Check the parameter specified by executing the following SQL:
select * from v$parameter
where name = 'open_cursors'
/

If you want more cursors to be opened at the same time, shut the database, change INITSID.ORA and restart the database.

The cursors that are counted for this are those explicit cursors that you opened and never closed or the cursors the PL/SQL keeps open. If you use a lot of stored procedures, then you will see lot of cached cursors. From release 8.1, PL/SQL will close these cached cursors on commit.

You can find the list of open cursors and the users who opened them by executing the following SQL:

select user_name, status, osuser, machine, a.sql_text
from v$session b,
v$open_cursor a
where a.sid = b.sid
/

But the above SQL will tell you about cursors opened at some point of time, but does tell you about currently open cursors. But the above SQL will helps us to track cursor leaks, which would need fixing, to avoid this error in the future.

The SQL given below will tell you how many are open truly.

select a.value, b.name
from v$mystat a, v$statname b
where a.statistic# = b.statistic#
and a.statistic#= 3
/

The closing of the cursor change based on the tool you use:

In JDBC, preparedStatement.close() does closes the cursor.
In PRO*C EXEC SQL CLOSE ; does it.
In OCI -- there is an API call to close a statement

These statements will make sure you close every explicitly opened cursor.

查询游标所在的应用程序和所在的中端(电脑):
select * from (
select terminal,program,count(*)  SQLCount from v$session
group by terminal,program)
order by SQLCount desc