Atchaya's Check Your Oracle Knowledge

Oracle - The self documenting dictionary Oracle's Data dictionary is itself self documenting. we can query DICTIONARY AND DICT_COLUMNS views for descriptions of the data dictionary views and their columns. The following query gives the descriptions of all of the data dictionary views. SELECT table_name, comments FROM dictionary ORDER BY table_name; It gives the large amount of output. By using where class we can focus a smaller set of views as like the following query. SELECT table_name, comments FROM dictionary WHERE table_name LIKE '%TABLE%' ORDER BY table_name It returns all views containing the word 'TABLE' Like wise We can query the DICT_COLUMNS view also. It gives the descriptions for the columns for all views. Following query retrieves descriptions for the columns in ALL_TAB_COLUMNS. SELECT column_name, comments FROM dict_columns WHERE table_name = 'ALL_TAB_COLUMNS'; This is a sample one. We can learn lot about oracle through data d...

Which SELECT statement will the result 'elloworld' from the string 'HelloWorld'? A. SELECT SUBSTR( 'HelloWorld',1) FROM dual; B. SELECT INITCAP(TRIM ('HelloWorld', 1,1)) FROM dual; C. SELECT LOWER(SUBSTR('HellowWorld', 1, 1) FROM dual; D. SELECT LOWER(SUBSTR('HelloWorld', 2, 1) FROM dual; E. SELECT LOWER(TRIM ('H' FROM 'HelloWorld')) FROM dual; Answer: E Explanation: TRIM function accept a string describing the data you would like to trim from a column value. It can trim from both side of column value i.e. left and right. In the following statement this functionwill trim as SELECT LOWER(TRIM ('+' FROM 'HelloWorld')) FROM dual; From the above statement trim function will remove the character 'H' from 'HelloWorld' and LOWER function will convert the remaining character to lower case.

Processes Oracle uses many small (focused) processes to manage and control the Oracle instance. This allows for optimum execution on multi-processor systems using multi-core and multi-threaded technology. Some of these processes include: PMON - Process Monitor SMON - System Monitor ARCn - Redo Log Archiver LGWR - Redo Log Writer DBWn - Database Writer CKPT - Checkpoint process RECO - Recoverer CJQn - Job Queue Coordinator QMNn - Queue-monitor processes Dnnn - Dispatcher Processes (multiplex server-processes on behalf of users) Snnn - Shared server processes (serve client-requests) MMAN - Internal process (used for internal database tasks) LSP0 - Logical standby coordinator process (controls Data Guard log-application) MRP - Media-recovery process (detached recovery-server process) MMON - Memory-monitor process MMNL - Memory monitor light (gathers and stores AWR statistics) PSP0 - Process-spawner (spawns Oracle processes) RFS - Remote file server process (archive to a remote site) DBRM ...