MySQL SELECT only not null values

You should use IS NOT NULL. (The comparison operators = and <> both give UNKNOWN with NULL on either side of the expression.)

SELECT * FROM table WHERE YourColumn IS NOT NULL;

Just for completeness I'll mention that in MySQL you can also negate the null safe equality operator but this is not standard SQL.

SELECT *FROM table WHERE NOT (YourColumn <=> NULL);

Edited to reflect comments. It sounds like your table may not be in first normal form in which case changing the structure may make your task easier. A couple of other ways of doing it though...

SELECT val1 AS valFROM  your_tableWHERE val1 IS NOT NULLUNION ALLSELECT val2 FROM  your_tableWHERE val2 IS NOT NULL/*And so on for all your columns*/

The disadvantage of the above is that it scans the table multiple times once for each column. That may possibly be avoided by the below but I haven't tested this in MySQL.

SELECT CASE idx         WHEN 1 THEN val1         WHEN 2 THEN val2       END AS valFROM   your_table        /*CROSS JOIN*/       JOIN (SELECT 1 AS idx                   UNION ALL                   SELECT 2) tHAVING val IS NOT NULL  /*Can reference alias in Having in MySQL*/

You can filter out rows that contain a NULL value in a specific column:

SELECT col1, col2, ..., colnFROM yourtableWHERE somecolumn IS NOT NULL

If you want to filter out rows that contain a null in any column then try this:

SELECT col1, col2, ..., colnFROM yourtableWHERE col1 IS NOT NULLAND col2 IS NOT NULL-- ...AND coln IS NOT NULL

Update: Based on your comments, perhaps you want this?

SELECT * FROM(    SELECT col1 AS col FROM yourtable    UNION    SELECT col2 AS col FROM yourtable    UNION    -- ...    UNION    SELECT coln AS col FROM yourtable) T1WHERE col IS NOT NULL

And I agre with Martin that if you need to do this then you should probably change your database design.

Select * from your_table WHERE col1 and col2 and col3 and col4 and col5 IS NOT NULL;

The only disadvantage of this approach is that you can only compare 5 columns, after that the result will always be false, so I do compare only the fields that can be NULL.