July 25, 2012

SQL Server 2012 IIF and CHOOSE




Continuing my series on SQL Server 2012, today we will explore two new conditional functions - IIF and CHOOSE in SQL Server 2012. IIF is a short form of the CASE expression

Consider the following example

declare @gender char(1)
set @gender ='M'
select case when @gender ='M' then 'Male' else 'Female' end as gender


The above t-sql code checks if @gender is 'M', return 'Male' else 'Female'

The same can be done using IIF as shown below

declare @gender char(1)
set @gender ='M'
select iif(@gender ='M','Male','Female')


You can also use IIF while selecting rows from a table column as shown below

create table #t(emp_id int, emp_name varchar(100),gender char(1), grade int)
GO

insert into #t(emp_id,emp_name, gender,grade)
select 1,'Suresh','M',1 union all
select 2,'Ramesh','M',3 union all
select 3,'Neela','F',2 union all
select 4,'Magesh','M',2 union all
select 5,'Sara','F',1

select emp_name,IIF(gender='M','Male','Female') as gender from #t

iif2

The CHOOSE function chooses the value from a list based on the ordinal position. If the value is 1, it chooses the first value, if it is 5, it chooses 5th value and so on from the list

The following can be used to illustrate what CHOOSE does

select emp_name,grade,CHOOSE(grade,'Manager','Project Leader','Developer') as grade_desc from #t

choose2

Based on the value available for the grade, it chooses between a 'Manager', 'Project Leader' or a 'Developer'

Both these expressions can be used to reduce the amount of code written using CASE expression


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About The Author

Madhivanan,an MSc computer Science graduate from Chennai-India, works as a works as a Lead Subject Matter Expert at a company that simplifies BIG data. He started his career as a developer working with Visual Basic 6.0, SQL Server 2000 and Crystal Report 8. As years went by, he started working more on writing queries in SQL Server. He now has good level of knowledge in SQLServer, Oracle, MySQL and PostgreSQL as well. He is also one of the leading posters at www.sqlteam.com and a moderator at www.sql-server-performance.com. His T-sql blog is at http://beyondrelational.com/blogs/madhivanan

 
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