Skip to main content

NVL,NVL2,DECODE,COALESCE functions in Oracle

By

All the functions mentioned in the above title are mainly used in evaluation of data whether it is null or not.
.
Lets see in details how these functions work and what are the differences between them

NVL

Syntax: NVL ( expr1 , expr2 )

 If the expr1 is null then expr2 value is returned, if expr1 value is not null then expr1 value is returned.

 NVL2

 Syntax: NVL2(expr1,expr2,expr3)

 if the expr1 is null then expr3 value is returned, if expr1 value is not null then expr2 value is returned.

COALESCE

 Syntax: COALESCE(expr1,expr2,expr3...)

it returns first non null expression value in the list.

DECODE

 Decode is enhanced version of case statement let me explain you with a sample query

 select
initcap(substr(pub_name,1,20)) publisher_name,
decode(book_type,'computer',1,0) media
from
publisher 
Here decode statement works like if the column book_type has computer value then it is returned as 1 else 0 

 Similar to case statement

 case when book_type='computer'
then 1
else 0
end media

 Hope this article helps you in understanding the above functions.

Comments

Post a Comment

Popular posts from this blog

Comparing Objects in Informatica

By
We might face a scenario where there may be difference between PRODUCTION v/s SIT version of code or any environment or between different folders in same environment. In here we go for comparison of objects we can compare between mappings,sessions,workflows In Designer it would be present under "Mappings" tab we can find "Compare" option. In workflow manger under "Tasks & Workfows" tab we can find "Compare" option for tasks and workflows comparison respectively. However the easiest and probably the best practice would be by doing using Repository Manager.In Repository Manager under "Edit" tab we can find "Compare" option. The advantage of using Repository manager it compares all the objects at one go i.e. workflow,session and mapping. Hence reducing the effort of individually checking the mapping and session separately. Once we select the folder and corresponding workflow we Can click compare for checking out ...
11 comments
Read more

Finding Duplicate records and Deleting Duplicate records in TERADATA

By Anonymous
Requirement: Finding duplicates and removing duplicate records by retaining original record in TERADATA Suppose I am working in an office and My boss told me to enter the details of a person who entered in to office. I have below table structure. Create Table DUP_EXAMPLE ( PERSON_NAME VARCHAR2(50), PERSON_AGE INTEGER, ADDRS VARCHAR2(150), PURPOSE VARCHAR2(250), ENTERED_DATE DATE ) If a person enters more than once then I have to insert his details more than once. First time, I inserted below records. INSERT INTO DUP_EXAMPLE VALUES('Krishna reddy','25','BANGALORE','GENERAL',TO_DATE('01-JAN-2014','DD-MON-YYYY')) INSERT INTO DUP_EXAMPLE VALUES('Anirudh Allika','25','HYDERABAD','GENERAL',TO_DATE('01-JAN-2014','DD-MON-YYYY')) INSERT INTO DUP_EXAMPLE VALUES('Ashok Vunnam','25','CHENNAI','INTERVIEW',TO_DATE('01-JAN-2014',...
2 comments
Read more

Target Load Type - Normal or Bulk in Session Properties

By
We can see the Target load type ( Normal or Bulk) property in session under Mapping tab and we will go for Bulk to improve the performance of session to load large amount of data. SQL loader utility will be used for Bulk load and it will not create any database logs(redolog and undolog), it directly writes to data file.Transaction can not be rolled back as we don't have database logs.However,Bulk loading is very as compared to Normal loading. In target if you are using Primary Key or Primary Index or any constraints you can't use Bulk mode. We can see this property in the below snap shot.
Post a Comment
Read more