How null values will work in update statement .

Database
The Teradata Database channel includes discussions around advanced Teradata features such as high-performance parallel database technology, the optimizer, mixed workload management solutions, and other related technologies.
Enthusiast

How null values will work in update statement .

Does null values will join in update statement ?

 

if both tables has null values source and target table  it wil consider null values and join ?

2 REPLIES
Senior Apprentice

Re: How null values will work in update statement .

No.

 

A null value will never match another null value in a simple comparison. In Teradata a NULL value is 'unknown' - how can the database know that two 'unknown' values are the same (or different).

 

You can say/code:

WHERE t1.col1 is NULL and t2.col1 is NULL

...but that is not comparing them directly.

 

HTH

Dave

 

Ward Analytics Ltd - information in motion
www: http://www.ward-analytics.com
Enthusiast

Re: How null values will work in update statement .

Thanks for your answer