CODEWITHSUNDEEP
mysqlsqlselectnotnull
bryan sammon
bryan sammon

Reputation: 7441

MySQL SELECT only not null values

Is it possible to do a select statement that takes only NOT NULL values?

Right now I am using this:

SELECT * FROM table

And then I have to filter out the null values with a php loop.

Is there a way to do:

SELECT * (that are NOT NULL) FROM table

?

Right now when I select * I get val1,val2,val3,null,val4,val5,null,null etc.... but I just want to get the values that are not null in my result. Is this possible without filtering with a loop?

Upvotes: 327

Views: 823516

Answers (12)

Abdul Samad Nizamani
Abdul Samad Nizamani

Reputation: 103

Add condition >0 for int columns and != "" for varchar columns

select column1_id, column2, colummn3, where column1_id>0 and column2 != ""

Upvotes: 0

Ricardo Erick Rebêlo
Ricardo Erick Rebêlo

Reputation: 17

You didn't even have to use an asterisk to get the table fields.

Upvotes: 0

rus
rus

Reputation: 1

WHERE COALESCE(ALL YOUR COLUMNS) IS NOT NULL

Upvotes: -3

Heba abd El monaem
Heba abd El monaem

Reputation: 5

SELECT duration,id FROM `tickets` WHERE duration !=""

Upvotes: -3

Basant
Basant

Reputation: 781

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 <>''

Upvotes: 5

Jonathan Vasiliou
Jonathan Vasiliou

Reputation: 162

Yes use NOT NULL in your query like this below.

SELECT * 
FROM table
WHERE col IS NOT NULL;

Upvotes: 2

Venkat Kallem
Venkat Kallem

Reputation: 25

SELECT * FROM TABLE_NAME
where COLUMN_NAME <> '';

Upvotes: -7

Alan Chavez
Alan Chavez

Reputation: 159

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.

Upvotes: 15

Martin Smith
Martin Smith

Reputation: 452957

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*/

Upvotes: 537

soulshake
soulshake

Reputation: 969

I use the \! command within MySQL to grep out NULL values from the shell:

\! mysql -e "SELECT * FROM table WHERE column = 123456\G" | grep -v NULL

It works best with a proper .my.cnf where your database/username/password are specified. That way you just have to surround your select with \! mysql e and | grep -v NULL.

Upvotes: 2

porquero
porquero

Reputation: 1169

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.

Upvotes: 8

Mark Byers
Mark Byers

Reputation: 837926

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.

Upvotes: 25

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