Answer Posted / dave
The dual table is a dummy table with one row and one column. Functions that do not require any table data can be evaluated by SELECTing from the dual table. For example,
SELECT SYSDATE FROM DUAL
returns the system time and date. The DUAL table is needed to get around the fact that the SELECT command in Oracle requires a FROM clause. For example, "SELECT SYSDATE" would fail because no tables were specified.
| Is This Answer Correct ? | 2 Yes | 1 No |
Post New Answer View All Answers
How would you go about verifying the network name that the local_listener is currently using?
how can a session indicate its interest in receiving alerts?
What is transparent data encryption? : sql server DBA
what is asm?
Which dictionary view(s) would you first look at to understand or get a high-level idea of a given Advanced Replication environment?
When setting replication, can you have distributor on sql server 2005, publisher on sql server 2008? : sql server DBA
how can you enable flashback feature?
How do you troubleshoot errors in a sql server agent job? : sql server DBA
Oracle client is not able to connect to Oracle server although tnsnames.ora file has valid enteries. Oracle error message is “ cannot resolve net service name”. Mention any three reasons.
how can you process messages in order asynchronously?
I have kept recovery catalog on same target database and taken backup of target DB to disk. deleted the target DB & tried to restore and revoer DB using the backup on disk but it is not possible, how do we restore & recover DB
Draft one mock email requesting your non-technical management grant you downtime to (provide justification where applicable) complete the following tasks: (1) Generate statistics on a large table; (2) Generate an RDA – if you don't know what an RDA is please say so. (3) Rename datafiles.
what is ora 24313?what is the procedure to exclude that error?
Define the SGA and: How you would configure SGA for a mid-sized OLTP environment? What is involved in tuning the SGA?
In which dictionary table or view would you look to determine at which time a snapshot or MVIEW last successfully refreshed?
