MySQL SELECT only not null values

Solution 1:

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 val
FROM  your_table
WHERE val1 IS NOT NULL
UNION ALL
SELECT val2 
FROM  your_table
WHERE 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 val
FROM   your_table
        /*CROSS JOIN*/
       JOIN (SELECT 1 AS idx
                   UNION ALL
                   SELECT 2) t
HAVING val IS NOT NULL  /*Can reference alias in Having in MySQL*/

Solution 2:

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

SELECT col1, col2, ..., coln
FROM yourtable
WHERE somecolumn IS NOT NULL

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

SELECT col1, col2, ..., coln
FROM yourtable
WHERE col1 IS NOT NULL
AND 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
) T1
WHERE col IS NOT NULL

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

Solution 3:

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.

Solution 4:

I found this solution:

This query select last not null value for each column.

Example

If you have a table:

id|title|body
1 |t1   |b1
2 |NULL |b2
3 |t3   |NULL

you get:

title|body
t3   |b2

Query

SELECT DISTINCT (

  SELECT title
  FROM test
  WHERE title IS NOT NULL 
  ORDER BY id DESC 
  LIMIT 1
) title, (

  SELECT body
  FROM test
  WHERE body IS NOT NULL 
  ORDER BY id DESC 
  LIMIT 1
) body
FROM test

I hope help you.

Solution 5:

Following query working for me

when i have set default value of column 'NULL' then

select * from table where column IS NOT NULL

and when i have set default value nothing then

select * from table where column <>''