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Sub query and correlated sub query
What is the difference between sub query and correlated sub query
krishnaindia2007
- Jun 20th, 2008
In sub query the inner query is executed only once. Depeding upon the results of inner query , outer query is evaluated.In correlated subquery the inner query is evaluated once for each row processed by the parent statement or outer query.
tariq_oracle
- Apr 13th, 2008
subquery: required in those cases where requisted data are not known and always depend on inner qu...
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Alias in Joins
Why do we use aliases during joining two tables?
krishnaindia2007
- Jun 20th, 2008
Alias name it temporary name given to a tablen or columns of a table.It has its existence until the satement is executed. For example in the following example instead of typing tablenames ...
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Arrange Date Week Wise
How to arrange date in week wise like from Monday to Sunday?
madhupriya.nukala
- Jun 26th, 2008
SELECT TO_CHAR(hiredate,'DAY') FROM emp ORDER BY to_char(hiredate-1,'D');
jannaat
- Apr 28th, 2008
Consider there is table H and you have 3 columns name week date so sql statement is select name ,week,date from H group by week order by date
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Analytical Function
WE using Last_value()analytical function but the result do not match according to me?
Raj_P
- Sep 1st, 2010
I am working on Oracle 9i and as far as I know the function "Last_Value" doesnt work in 9i. We are using the "First_Value" function with order by clause using descending order. Select First_Value(FieldName) Over (Partition by FieldName Order by TrandDate Desc) From .
Avashisth
- Feb 20th, 2010
Analytical function are the builtin function in Oracle, so during execution it will be faster then other simple function. These function are basically used for reporting and most of the time to improv...
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Base table of View table
How do we view the query used while creating a View table? i.e How to find the dependencies of a view table.
sinhasaurabh014
- Sep 4th, 2008
If you have toad, you can see everything. Just navigate to view throgh schema browser and check under the tabs "view". select your view and check all the properties from it.
vermapradeep1980
- Aug 30th, 2008
Try this one.. select text from user_view where view_name ='viewname'pradeep
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Securing SQL Scripts
How to secure SQL scripts so that they cannot be seen by others but can only be executed.
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LOCK Query
What is use of lock query in SQL Plus? Give its syntax and implementation?
sampra
- Mar 6th, 2012
Exclusive Lock: This is placed when Insert, Update or Delete command is performed. There can be only one exclusive lock on a record at a time.
hussasha
- Mar 17th, 2009
Locking protect table when several users are accessing the same table. Locking is a concurrency control technique in Oracle. It helps in data integrity while allowing maximum concurrency access to...
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SELECT Statement in CASE
How to use select statement in Case?
sunraajkumar
- Jun 3rd, 2009
Example sample query: if then else conditionSELECT empno, ename,
job, sal,
CASE job WHEN 'manager' THEN sal *0.10
WHEN 'analyst' THEN sal *0.20
WHEN 'president' THEN sal *0.30
ELSE sal END "Revised Salary" from emp; -
Ref Cursors
How many ref cursors can be dynamically opened in stored procedures for a session?
kondapallikalyan
- Nov 24th, 2009
We have two types of ref cursors1. Week typed2. Strong typedEx: Type <Ref cursor Name> is ref cursor /* this is week typed*/Ex:Type <Ref cursor Name> is ref cursor return /* this is strong type
sunraajkumar
- Jun 10th, 2009
more then one query open same cursor name at same time (use unlimited query)
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SQL Soundx
What is soundx in SQL?
sure_prince
- Aug 14th, 2009
This is Soundex Function is useful to select the data according to the sound of
the given value but not compare with the casing of that letters.For Example:
SQL> SELECT * FROM emp WHERE Soundex(Ename)=Soundex('Analyst');
It select all the Analyst details in emp table in anuy case...sunraajkumar
- Jul 1st, 2009
Soundex function is used to find the phonetic representation of stringSyntax----------Soundex(CHAR)Query--------SELECT Empname FROM Employee WHERE SOUNDEX(EMPNAME)=SOUNDEX('SMYTHE')
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SQL System Time
How to get System time in SQL?
kondapallikalyan
- Nov 24th, 2009
We have Functions1. current_timestamp2. systimestampEx: Select current_timestamp from dual;Ex:Select systimestamp from dual;
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Change Default Display
How to change the default display? For deptno 10 show "Financial Department", for deptno 20 show "Account Department", for deptno 30 show "Management Information System", for deptno 40 show "Electronic Data Processing"
kiran_marla
- Jun 20th, 2010
Use decoding to display names.select decode(deptno,10,'Financial Department',20,'Account Department',30,'Management Information System',40,'Electronic Data Processing'...
Kushy14
- Jun 19th, 2010
SELECT DECODE (deptno,10,'Financial Department',20,'Account Department',30,'Management Information System',40,'Electronic Data Processing') FROM dept;
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Number of Constraints
How to count the number of constraints on a given table?
itoradeveloper
- Jan 6th, 2010
Select count(constraint_name) from user_constraints where table_name='TABLENAME'
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Aggregation Key
What is the Aggregation Key?
AnithaLetchumi
- Aug 10th, 2011
Aggregation Key is nothing but composite or concatenated key. It's the primary key having more than one column. For example different books may have identical titles, authors. In this case we can take...
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Create Index
How Create Index in Oracle? explain with example
sampra
- Mar 6th, 2012
Create index cr_ind on student(sid);
here i have created a index on student table on column sidprashant.baranwal
- Sep 16th, 2010
The CREATE INDEX statement is used to create indexes in tables. Indexes allow the database application to find data fast; without reading the whole table. CREATE INDEX index_name ON table_name (c...
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Oracle query performance
A) I have 100 columns in emp table , which of the below queries will give good performance and WHY?1) Select * from emp;2)select col1,col2,col3,..............col100 from emp;B) we have 2 tables T1(100 records) and T2(1000) recordsWhen we use the below queries , it will generate Cartesian product , which query will give better performance and WHY?1)Selct * from t1,t2 ;2)select * from t2,t1;
DSADSF
- Sep 24th, 2011
SELECT * FROM T1,T2
WHERE T1.COLUM_NAME=T2.COLUM_NAME;
NOTE THAT COLUMN NAME AND DATA SHOULD BE SAMEnandha_spartan
- Aug 18th, 2011
Set time on
then
write the query then execute display output and timing..
then write set time off
write same query then execute display output ,compare both timing it is called query performance -
SQL Query to retrieve columns having a particular character
Table StructureID Name Salary1 Pratap 15002 Gayathri 25003 Anita 3000 4 Ram.C 4500Write a query to retrieve names which have the letter R in it irrespective of the case(small or caps).Output:ID Name Salary1 Pratap 15002 Gayathri 25004 Ram.C 4500
Sanjay Bajracharya
- Jul 13th, 2011
Code- span style="color: #ff0000;">'%R%';
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Case and decode
can anyone help with a simple example of converting one from other like CASE to DECODE or DECODE to CASE.
Mark Haynes
- Oct 12th, 2011
Sorry about that seems some of the info got stripped out of my examples, so once again: CASE "expression" WHEN "search condition 1" THEN "return value 1" ELSE "return else ...
Mark Haynes
- Oct 12th, 2011
Both CASE and DECODE function as IF-THEN-ELSE statements: (limit your conversions to SQL statements in Oracle only) CASE WHEN THEN ELSE END converts to: DECODE(, , ,...
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Outer Join
When will we use outer join? Explain with example
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Oracle SQL Interview Questions
Ans