Where field null sql

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. If field is null, pull certain fields; otherwise, pull other fields Ask Question. Asked 9 years, 9 months ago. Active 6 years, 1 month ago. Viewed 36k times. Improve this question.

Burhan Ali 2, 1 1 gold badge 25 25 silver badges 38 38 bronze badges. Sesame Sesame 3, 16 16 gold badges 47 47 silver badges 73 73 bronze badges. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our terms of use , cookie and privacy policy. Copyright by Refsnes Data. All Rights Reserved. This gives us the correct result.

You can try different literals to see that, no matter what value you compare to the column values, rows with a NULL value will be excluded. Sorting data in nullable columns also has its secrets. Going a little further, we can combine the two previous examples into one query with the UNION clause:. By doing this, we can get all the Springfield folks, either married or single, in one result set:.

Null elements are very useful for representing real-life situations where a piece of information is absent. But they should be used with caution to avoid adversely affecting the integrity of the information contained in the database. Need to get deeper into SQL practice? However, this query cannot use the created non-clustered index so it will read all index pages and then return the appropriate rows.

To eliminate this situation, we can make a little code modification in the query so that the query optimizer can use the indexes more efficiently. The following query returns some rows as like the previous one but it uses the indexes more efficiently.

FROM Person. USE [ AdventureWorks ]. ON [ Person ]. Author Recent Posts. Esat Erkec. His current interests are in database administration and Business Intelligence.