SQL Server null value issue

Question

When executed the following query it is returning null.

Explanation: the longitude is a varchar column, many rows are there having longitude = null but this query did not return anything.

I thing I am missing a minute thing.

select * from fb_event where longitude =null

This is not a SQL Server issue - reading an indtroduction into SQL is needed, XXXcoder. Trinary logic is the same in all SQL implementations for a good reason. — TomTom
– TomTom, Commented Nov 2, 2011 at 6:29

marc_s · Accepted Answer · 2011-11-02 06:27:35Z

4

Your where clause should read where longitude is null.

Null does not equal null, so you must use "is" instead of "=".

edited Nov 2, 2011 at 6:27

marc_s

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answered Nov 2, 2011 at 6:22

Scott Bruns

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2 Comments

marc_s Over a year ago

+1 NULL really isn't a value - it's the absence of a value - therefore you cannot use the regular value comparison

TomTom Over a year ago

More exact as NULL is unknown, comparing one unknown with another can not ever be true - NULL != NULL. NULL also destroys values. SUM with one item NULL is also NULL (unknown).

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