Oracle basics-5

264. empty_ B | clob ()
Returns an empty lob locator, which is used to initialize the lob variable or to insert or update declarations.
Initialize the lob column or set its attribute to null.
Insert into Table1 values (empty_blob ());
Update Table1 set clob_col = empty_blob ();
265. bfilename ('Directory ', 'filename ')
Returns a bfile locator. The related binary lob physical files are stored in the file system of the server. Directory
Directory refers to the alias of the full name of the actual search path on the file system of the server. filename refers to the server
File name of the file system.
Insert into file_tab values (bfilename ('lob _ dir', 'image1. gif '));
266. Greatest (expr, expr ,...)
Greatest returns the maximum value of the parameter.
Select greatest ('Harry ', 'harriot', 'harold') 'sample' from Table1;
267. Least (expr, expr ,...)
Least returns the minimum value of the parameter.
Select least ('Harry ', 'harriot', 'harold') 'sample' from Table1;
268. nls_charset_decl_len (bytecnt, csid)
Returns the width of an nchar column.
Select nls_charset_decl_len (200, nls_charset_id ('ja16eefdfdf ') from
Table1;
269. nls_charset_id (text)
Returns the number of NLS Character Set IDs corresponding to the NLS Character Set Name.
Select nls_charset_d ('jadfdffdf ') from Table1;
270. nls_charset_name (N)
Returns the NLS Character Set name corresponding to ID n.
Select nls_charset_name (2) from Table1;
271. nvl (expr1, expr2)
If expr1 is null, expr2 is returned; otherwise, expr1 is returned.
Select name, nvl (to_char (Comm), 'not application') from Table1;
272. uid
Returns the integer that uniquely identifies the current database user.
Select uid from Table1;
273. User
Returns the name of the current Oracle user using the varchar2 data type.
Select User, uid from Table1;
274. userenv (option)
Returns the current session information.
Option = 'isdba ': true if the current role is a DBA; otherwise, false.
Option = 'language' returns the character set of the database.
Option = 'sessionid' is the current session identifier.
Option = 'entryid' returns the auditable session identifier.
Option = 'lang 'returns the ISO Note of the session language name.
Option = 'instance' returns the current instance.
Select userenv ('language') from dual;
275. vsize (expr)
Returns the number of bytes in expr.
Select name, vsize (name) from Table1;
276. deref (E)
Returns the object reference of parameter E.
Select deref (C2) from Table1;
277. reftohex (r)
Convert the R parameter to hexadecimal notation.
Select reftohex (C2) from Table1;
278. make_ref (table, key, key ...)
Use the given key as the primary key to create a row Reference in the given view object.
Create Type T1 as object (a number, B number );
Create Table tb1 (C1 number, C2 number, primary key (C1, C2 ));
Create view V1 of T1 with object OID (A, B) as select * From tb1;
Select make_ref (V1, 1, 3) from pubs;
279. stddev (distinct | all X)
Stddev returns the standard deviation of a group of row values.
Select stddev (salary) as example from employee;
280. Variance (distinct | all X)
Variance returns the variance of all values in a group of rows.
Select variance (salary) as example from employee;
V$ view managed by 9i
281. V $ access
Displays the objects in the currently locked database and the sessions that are accessing them.
282. V $ active_instances
Creates a ing from Instance name to instance number for all instances in the currently installed database.
283. V $ active_sess_pool_mth
The method for allocating all active session pool resources.
284. V $ AQ
The queue statistics in the current database.
285. V $ Archive
Archive the information in the required redo log file.
286. V $ archive_dest
All the archive log target files of the current instance and their current values, modes, and statuses.
287. V $ archive_processes
Provides information about different arch process statuses for an instance.
288. V $ archive_log
Archive log information in the control file.
289. V $ backup
Backup status of all online data files.
290. V $ backup_async_io
The backup set information is displayed in the control file.
291. V $ backup_0000uption
The control file displays corrupted information in the data file backup.
292. V $ backup_datafile
The backup data file and backup control file are displayed in the control file.
293. V $ backup_device
Displays information about supported backup devices.
294. V $ backup_piece
The backup block information is displayed in the control file.
295. V $ backup_redolog
Information about archiving logs in the backup set is displayed in the control file.
296. V $ backup_set
The backup set information is displayed in the control file.
297. V $ backup_sync_io
The backup set information is displayed in the control file.
298. V $ bgprocess
Describes the background process.
299. V $ BH
Is the 9i real-time application cluster view, which provides the status and number of probes for each buffer in the global zone of the system.
300. V $ BSP
Displays the statistical information used in the background process of the cache block server.
301. V $ buffer_pool
Displays information about the instance buffer pool.
302. V $ buffer_pool_statistics
Displays information about the instance buffer pool.
303. V $ Cache
Contains the header information of each block in the SGA of the current instance.
304. V $ cache_lock
Contains the header information of each block in the SGA of the current instance. It is very similar to V $ cache,
Except for the identity symbols of the Special Envoy platform lock manager.
305. V $ cache_transfer
The function is the same as that of V $ cache except that the information of the blocks that have been probe at least once is displayed.
306. V $ Circuit
Contains information about virtual circuits. It refers to all connections from the user to the database through the scheduler and server.
307. V $ class_ping
Displays the number of probe blocks in each block class.
308. V $ compatibility
Displaying the features used by the database instance can prevent the database from returning to earlier versions.
309. V $ compatseg
Display the permanent features used by the database instance to prevent the database from returning to earlier versions.
310. V $ Context
Lists the setting attributes of the current dialog.
311. V $ controlfile
Lists the names of control files.
312. V $ controlfile_record_section
Displays information about the control file record.
313. V $ copy_partition uption
Displays corrupted data files in the control file.
314. V $ cr_block_server
Displays the statistical information used in the background process of the cache block server.
315. V $ Database
Contains the database information in the control file.
316. V $ datafile
Contains information about the database files in the control file.
317. V $ datafile_copy
Contains the database file copy information in the control file.
318. V $ datafile_header
Displays the data file information in the data file header.
319. V $ db_cache_advice
The number of physical reads is estimated based on the cache size.
320. V $ db_object_cache
Database objects cached in the database cache.
321. V $ db_pipes
Displays the pipeline currently depicted by the shared pool in the instance.
322. V $ dbfile
Lists All data files that make up a database.
323. V $ dblink
Query all database connections opened by a session.
324. V $ deleted_object
Displays the deleted archived logs in the control file.
325. V $ dispatcher
Provides information about the scheduling process.
326. V $ dispatcher_rate
Provides high-quality rate statistics for scheduling processes.
327. V $ dlm_all_locks
Lists information about all current locks.
328. V $ dlm_convert_local
The time consumed by the local lock conversion operation.
329. V $ dlm_convert_remote
The time consumed by the remote lock conversion operation.
330. V $ dlm_latch
It is outdated, see V $ Latch
331. V $ dlm_locks
These are the lock information known by the lock manager to be blocked or blocked by other objects.
332. V $ dlm_misc
Multiple DLM statistics are displayed.
333. V $ dlm_ress
Displays information about all resources known to the current lock manager.
334. V $ enabledprive
Displays the granted privileges.
335. V $ enqueue_lock
Displays all locks owned by the queue object.
336. V $ event_name
Contains information about the waiting event.
337. V $ execution
Displays information in parallel execution.
338. V $ false_ping
The buffer zone that failed the probe may be obtained.
339. V $ fast_start_servers
Information about all slave operations that execute parallel operation transaction recovery.
340. V $ fast_start_transactions
Transaction progress information in recovery.
341. V $ file_cache_transfer
Displays the number of blocks explored in each data file.
342. V $ file_ping
Displays the number of blocks under exploration for each data file.
343. V $ filestat
Contains the read/write statistics of the file.
344. V $ fixed_table
Displays all dynamic performance tables and views in the database and export tables.
345. V $ fixed_view_definition
Displays the definitions of all fixed views.
346. V $ gc_elements_with_collisions
You can find the lock to protect multiple caches.
347. V $ ges_blocking_enqueue
These are the lock information known by the lock manager to be blocked or blocked by other objects.
348. V $ ges_convert_local
Local lock Conversion
349. V $ ges_convert_remote
The time consumed by the remote lock conversion operation.
350. V $ ges_enqueue
Displays all the locks that the current lock administrator knows.
351. V $ ges_latch
See V $ Latch
352. V $ ges_resource
Displays information about all resources known to the current lock manager.
353. V $ ges_statistics
Multiple DLM statistics are displayed.
354. V $ global_blocked_locks
Displays the global block lock.
355. V $ global_transaction
Displays information about the currently activated global transaction.
356. V $ hs_agent
Identifies the set of HS proxies currently running on a given host.
357. V $ hs_session
The HS session set opened by the Oracle server.
358. V $ indexed_fixed_column
Displays the columns (x $ table) in the index-created dynamic performance table ).
359. V $ instance
Displays the status of the current instance.
360. V $ instance_recovery
It is used to monitor and execute the user-specified limit on the number of restored reads.
361. V $ Latch
List statistics for non-parent simple locks.
362. V $ latch_children
The statistic of the sub-simple lock.
363. V $ latch_misses
Attempts to obtain a statistical statement for simple lock failures.
364. V $ latch_parent
Contains the statistics about the easy-to-use locks of both parents.
365. V $ latchholder
Information of the owner of the current simple lock.
366. V $ latchname
Contains information about the names of simple locks displayed in V $ latch.
367. V $ librarycache
Statistics on high-speed cache performance and activity.
368. V $ license
License restriction information.
369. V $ loadcstat
Contains the SQL * loader statistics compiled during direct loading and execution.
370. V $ lock
The current Oracle lock.
371. V $ lock_activity
Displays the DLM lock activity of the current instance.
372. V $ lock_element
Each cached PCM lock has an entry in V $ lock_elements.
373. V $ locked_object
Lists all the locks obtained by each firm.
374. V $ lock_with_collisions
You can query the locks that protect multiple buffers.
375. V $ log
The information of log files in the control file.
376. V $ log_history
History of log files in control files.
377. V $ logfile
Contains information about the redo log file.
378. V $ loghist
The log history information of the log file in the control file.
379. V $ logmnr_contents
Log history.
380. V $ logmnr_dictionary
Log history.
381. V $ logmnr_logs
Log information.
382. V $ logmnr_parameters
Log information.
383. V $ MTS
Contains information about the server that adjusts multiple threads.
384. V $ mystat
The statistics of the current session.
385. V $ nls_parameters
The current NLS parameter information.
386. V $ nls_valid_values
Lists the valid values of all NLS parameters.
387. V $ object_dependency
You can determine which object to depend on by the package, process, or cursor currently loaded in the shared pool.
388. V $ object_usage
To monitor the use of indexes.
389. V $ obsolete_parameter
Lists obsolete parameters.
390. V $ offine_range
Displays the offline information of data files in the control file.
391. V $ open_cursor
Lists the opened and parsed cursors of each session.
392. V $ Option
List the status of Oracle service installation.
393. V $ parallel_degree_limit_mth
Display all valid methods for limiting Resource Allocation in concurrency.
394. V $ Parameter
Lists information about initialization parameters.
395. V $ parameter2
Lists the parameters and parameter values that affect the current session.
396. V $ pgastat
Lists Oracle memory usage statistics.
397. V $ Ping
Same as V $ cache.
398. V $ pq_sesstat
Lists the statistics of parallel queries.
399. V $ pq_slave
The statistics of the server that executes each activity in parallel on an instance.