How to update column with null value

I am using mysql and need to update a column with a null value. I have tried this many different ways and the best I have gotten is an empty string.

Is there a special syntax to do this?

No special syntax:

CREATE TABLE your_table (some_id int, your_column varchar(100));

INSERT INTO your_table VALUES (1, 'Hello');

UPDATE your_table
SET    your_column = NULL
WHERE  some_id = 1;

SELECT * FROM your_table WHERE your_column IS NULL;
+---------+-------------+
| some_id | your_column |
+---------+-------------+
|       1 | NULL        |
+---------+-------------+
1 row in set (0.00 sec)

NULL is a special value in SQL. So to null a property, do this:

UPDATE table SET column = NULL;

Use IS instead of = This will solve your problem example syntax:

UPDATE studentdetails
SET contactnumber = 9098979690
WHERE contactnumber IS NULL;