Conditional null not null in a select statement column - SQL Server

Question

Please take a look at this and let me know the possible solution?

Data to be shown from the table:

select a,b,d,e from table xyz.

when c is null show d with value

or

when c is not null show e with value

Data required:

Data looks like this

a b  c          d e 
1 2  null         2
1 2  not null   2

From the above data, if c is null, display d = b else e = b.

How to write a proper SQL query for the above conditions, as I tried case it is not working.

Thanks in advance.

You want to try again. Specs like this from customers are excusable... — Tony Hopkinson
– Tony Hopkinson, Commented Jul 30, 2013 at 21:40

Doug Morrow · Accepted Answer · 2013-07-30 21:49:54Z

2

SELECT CASE WHEN c IS NULL THEN d ELSE e END

The bit about display d = b else e = b leads me to believe you may also be trying to compare NULL and NOT NULL values.

It's important to understand that SQL NULL means "Unknown" and therefore a comparison cannot take place between a known value and an unknown value.

In this case I suggest the use of Coalesce to change the value when it is NULL to something comparable that will not affect your logic.

Coalesce(d, 0) = b

answered Jul 30, 2013 at 21:49

Doug Morrow

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Steven Wexler · Accepted Answer · 2013-07-30 22:04:28Z

1

SELECT CASE WHEN c IS NULL THEN d ELSE e END

edited Jul 30, 2013 at 22:04

answered Jul 30, 2013 at 21:36

Steven Wexler

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1 Comment

Bridge Over a year ago

You're missing a keyword. The correct syntax here is: SELECT CASE WHEN c IS NULL THEN d ELSE e END

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