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How centralized DBMS differs from distributed DBMS .
ambika
- Oct 21st, 2013
Recovery in centralized dbms
su4surya
- Aug 24th, 2009
A centralized database has all its data at one place so there may occur problems of data avalability, and a system crash may lead to whole dataloss. In a distributed database, database is stored on se...
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Pair Wise & Non-Pair Wise Columns
What are Pair Wise & Non-Pair Wise Columns?
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There is a % sign in one field of a column. What will be the query to find it?
'' Should be used before '%'.
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Difference between nested query,sub query and nested query?
What is difference between nested query,sub query and nested query? explain clearly with an example?
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arpitapatel- Member Since Sep-2008 | Sep 24th, 2008
Query inside the query is nested query.
It is also called as sub query.
Correlated subquery runs once for each row selected by the outer query. It contains a reference to a value from the row selected by the outer query.
Nested subquery runs only once for the entire nesting (outer) query. It does not contain any reference to the outer query row.rams
- Apr 3rd, 2012
Both are same
katgeektalk
- Aug 22nd, 2010
The subquerry is often reffered to as a nested SELECT, sub-SELECT, or inner SELECT statement. The subquery generally excuted first, and its output is used to complete the query condition for the main (or outer) query.
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What is the Querry for retrieving the 2nd highest salary in a table?
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muralir02- Member Since Mar-2006 | Mar 20th, 2006
select max(sal) from emp where sal<(select max(sal) from emp);
sampra
- Mar 6th, 2012
Select salry from Hello h where 2=(select count (distinct salry) from hello where h.salry
srivathson
- Feb 20th, 2012
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Rename a Column
How to rename a column in a SQL table?
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sravee123- Member Since May-2008 | Jun 10th, 2008
ALTER TABLE table_name RENAME COLUMN old_name to new_name;
Ex: ALTER TABLE employee RENAME COLUMN eno to empno;karthickrfwin
- Sep 22nd, 2011
Use this Script for nename particular ColumnName in SqlTable
sp_rename 'TableName.[ColumnNameOld]','[ColumnNameNew]','Column'
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How many columns can be in the group by clause
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Srinivas4u- Member Since Jul-2008 | Jul 16th, 2008
I am sure that a group by clause can have all columns which are there in that table,not sure if you are looking for anotehr answer
akshya dash
- Jul 25th, 2011
there can be n no of columns in a group by clause other than group functions for ex select ename, deptno max(sal) from emp group by ename,deptno; here max(sal) is a group function and ename and ...
sasanka
- Jul 21st, 2011
In GroupBy clause contains the no of columns in the select Statement to retrieve the data.
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Is there any way we can change the column name in a table
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Answered by: Praveena
- Dec 14th, 2005
Yes we can alter Column name in a table using the following query:
alter
table <tablename> rename column <old Column Name> to <New Column Name>Regards,
Praveena
dude_8550
- Jun 15th, 2011
U can change the column name and also column definition that is whether the data type and its size by the ALTER command.ALTER TABLE RENAME COLUMN <old column name> TO <new coumn name>;
Santhoshkandula
- May 11th, 2011
yes, it's possible to change the column name by using the following query in SQL server SP_RENAME ' <TABLE_NAME.OLD_COLUMN_NAME> ' , ' NEW_COLUMN_NAME ' Thanks & Regards K.Santhosh
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Can we call a function in sql query and what are the pre requisites to call a function in sql query?
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Answered by: Jayakumar M
- Nov 8th, 2005
Yes. We can call Functions from SQL statements.
To be callable from SQL statements, a stored function must obey the following
"purity" rules, which are meant to control side effects:
When called from a SELECT statement or a parallelized INSERT, UPDATE, orDELETE
statement, the function cannot modify any database tables.
When called from an INSERT, UPDATE, or DELETE statement, the functioncannot query or modify any database tables modified by that statement.
When called from a SELECT, INSERT, UPDATE, or DELETE statement, thefunction cannot execute SQL transaction control statements (such as
COMMIT),session control statements (such as
SET ROLE), or system control statements(such as
ALTER SYSTEM). Also, it cannot execute DDL statements (such asCREAT
E) because they are followed by an automatic commit.planet100
- Apr 19th, 2011
I have a question... what if the function returns long??i am not able to use in the select query.It says " ORA-00997: illegal use of LONG datatype " .Is there any other way to address this, ...
nis1981
- Aug 3rd, 2008
Yes, you can call function in sql query, these functions should be in-built or predefined in the DBMS.
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List all the employees who have atleast one person reporting to themList the employee details if and only if more than 10 employees are presently in department 10
krishsidd
- Nov 26th, 2010
CREATE TABLE EMP ( EMPNO NUMBER(4) NOT NULL, ENAME VARCHAR2(10), JOB VARCHAR2(9), MGR NUMBER(4), HIREDATE DATE, SAL...
yagneswarasankar
- Nov 24th, 2010
1 select manager_id,last_name,count(employee_id) over (partition by manager_id ) cnt from employe 2* order by cntSQL> /MANAGER_ID LAST_NAME &nb...
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View - Base Tables
Does View occupy memory? If we delete the base table of existing view, What happens?
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Mad Hatter- Member Since Nov-2008 | Nov 4th, 2008
View does not occupy memory, but Oracle keeps view code in its dictionary (you can check in user_views, for example)
If you delete the base table, the view becomes INVALID.
In order to make it valid again, you have to ether build the deleted table again, or create anotehr view with the same name and structure as deleted table, or create synonym with the same name as deleted table, which will point to the table with the same structure.pkshve
- Sep 12th, 2010
Views are database objects - they are just SQL code stored in database which will be executed every single time the view is called. Database will check the existance of columns and tables in the base ...
manimehra905
- May 18th, 2010
View does not occupy memory as it only provides a way for watching multiple views of an object: Table. Moreover, it is a virtual table which does not take space.It provides DATA HIDING.For e.g. i...
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HAVING vs WHERE Clause
Where clause restricts rows, what does having clause restricts ?1. only group results.2. rows results.3. both rows and groups result.
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ajaysinghnegi- Member Since Mar-2009 | Mar 27th, 2009
1) HAVING clause can only be used to filter out the aggegate functions whereas WHERE clause cannot filter out the aggegate functions.
2) HAVING clause can be used with GROUP BY function where as WHERE clause cannot be used with group by function.gubba123
- Aug 8th, 2010
Example: Write a query to display the Managers who are working for more than one Departments:Select emp_id, count(distinct dept_id) From emp Where...
Tartauris
- Feb 16th, 2010
Having is used for agregate results while where is used for unagregated results.
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How will you delete duplicating rows from a base table?
Delete from table_name where rowid not in (select max(rowid) from table group by duplicate_values_field_name); ordelete duplicate_values_field_name dv from table_name ta where rowid <(select min(rowid) from table_name tb where ta.dv=tb.dv);
thirupathireddy
- Feb 2nd, 2010
DELETE FROM table_name a WHERE rowid > (SELECT min(rowid) FROM table_name b WHERE a.column_name=b.column_name)
syam sundar
- Aug 18th, 2007
Delete table_name t1where rowid>(select rowid from table_name t2)and t1.column1=t2.column1
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Is it possible to create Synonym for Triggers ?
If your answer is yes, explain the steps.
gkbiswal
- Sep 29th, 2007
Yes we can.create or replace trigger trg_testbefore insert on empbeginnull;end;create synonym trg_syn for trg_test;
Oracle SQL Interview Questions
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