Database Admin Interview Questions

I will refer predominantly to Relational DBMS. In a file system, data is contained in a flattened structure that is often a variable length structure. For example, a shipment received could contain th...

DDL is used to create, alter and truncate
DML is used to insert, update, delete and drop

DDL means "Data Definition Language". SELECT, UPDATE, INSERT belong to DML, which is "Data Modification Language". DDL is all the other commands -- for example, CREATE TABLE.

Alter table A add column address1 varchar2(10);

Unsing Pivot Query

You can make use of VSIZE function to get the number of bytes in the internal representation of individual field. However this cannot be applied on fields that has BLOB data type and in such case you have to use dbms_lob.getlength function on BLOB data type field.

Online backup also known as hot backup / open backup can be performed even the database is open and while users are working and is available for read and write activity. To perform Online backup, the ...

There are few ways through which you would find if your database uses recovery catalog: Check backup scripts and findout if the scripts are making any connection to a recovery catalog. Check tnsnames...

SORT_AREA_SIZE is one of the deferred Oracle Server Parameters which is set in init.ora. Its value as bytes (integer) sets the size of in-memory sort work area. The default is 64K and the maximum valu...

Yes We can Take of Controlfile Online Mode Just
Fire The Command alter database backup controlfile trace And
alter database backup controlfile as trace '/Location where u want 2 take backup of ctlfile/';

No, we can not take backup of redo log files even database is running in archive log mode because of inconsistency

just create the datafile with same location mention in ur controlfile and recover the datafile ... Its simple.

alter database create datafile 'and give the datafile location and /name' by using this command we can recover the datafile without backup also

show sga;

we can see the memory of SGA space

Whats the process of refresh ? ( I mean steps). Do you export/import or we take a differential backup and restore on test DB ? Any links to an article will be of great help.

Hi, There is little diff between them. First we clone the d.b totally(homepath,datafiles,data.....etc) from Prod to Test, where as in D.B Refresh we just refresh the additional data which is in p...

1- When BEGIN BACKUP is issued: The hot backup flag in the datafile headers is set, so that the copy is identified to be a hot backup copy. This is to manage the backup consistency issue when the cop...

Sql>alter database begin backup;The above query is used to freeze the header of all datafiles belongs to tablespace in that particular database.Freeze means lock i.e during backup no data's wil...

in our project to kill all the inactive session we use the following script.. run the sql script given below it will give u all inactive sessions sid and serial no and redirect output to (inactive_kil...

Assuming you need lines 20 to 40,

sed -n '20,40p' file_name

or

awk 'FNR>=20 && FNR<=40' file

Hope it will help!

Order By is a keyword which is using for sort the table records either ascending or desending.For eg,for ascending,Select emp_name,emp_identity from emp order by emp_identity;Select emp_name...

contents or data of the table can be sorted by using clause ORDER BY  in SELECT statement.By default the table is in ASCENDING order.SYN: SELECT  * from [table name]    &...

We can also see these connections on Activity monitor. But you need permissions to see it.

We can determine the number of connections by using this - SELECT COUNT(*) FROM v$session;

There is no need to issue commit command after executing DDL statements as the DDL statements are commited automatically

 Dear Mam/Sir ,

NO NEED TO COMMIT AGAIN USING DDL STATEMENTS .