Check if value is null, if it is , print nothing, else, print value. Help?

Question

Right, I'm still new to PHP/MySQL and what I've got, even in my head, sounds like it should be simple, but I just can't work out how to write it, here's what I want to happen:

MySQL statement get's the value's of all the cells where the row = id, PHP then prints them in the appropriate places (this bit I can do), If a value in said row is null, I don't want it to print ANYTHING related to that value, Else, continue as normal.

I.e:

-- Other code --

if (value where id = id == null) {

}
else {
Twitter: @Twitter
}

Are you trying to write SQL or PHP? – Matt Ball Aug 11 '11 at 10:46 — Matt Ball, Aug 11 '11 at 10:46

score 3 · Accepted Answer · answered Aug 11 '11 at 10:45

3

What is your exact problem? A simple if statement would do just fine.

$result = mysql_query("SELECT * FROM somewhere");

while($row = mysql_fetch_assoc($result))
{
 if($row['someValue'] != '')
 {
  echo $row['someValue'];
 }
}

answered Aug 11 '11 at 10:45

TJHeuvel

12,403
4
37
46

There's always a possibility that the database contains values that are nothing but white-space. A `trim` might help in that case either in PHP or in SQL. In MySQL trim only apparently works on spaces though. – Aleksi Yrttiaho Aug 11 '11 at 10:53
I'd have to agree, try to check in your SQL query whether the particular field is empty. This will be more performant. – TJHeuvel Aug 11 '11 at 11:04

score 2 · Answer 2 · edited May 23 '17 at 11:55

Using SQL you can limit the number of rows that the program has to fetch. To ignore all rows where any of the column values is null, you define a IS NOT NULL condition for each column you require to be not null. For example

SELECT id, label value 
FROM my_very_special_Table
WHERE id = ?  
  AND label IS NOT NULL
  AND value IS NOT NULL

Now there's always a possibilty you have empty string or strings with only white space. MySQL seems to distinguish an empty string from a null value unlike at least Oracle i.e. '' <> NULL is true.

In this case you'll have to modify the conditions to make things work properly with VALUE <> '' or LENGTH(VALUE) > 0. You can add trimming to clear spaces, but in MySQL, trim doesn't remove any other white-space characters. You can also match agains a regular expression but that's probably a bit slow.

If you happen to have both null values and empty strings, you have to cover both scenarios.

The better solution, anything else is sympton fixing! – Wesley van Opdorp Aug 11 '11 at 10:53 — Wesley van Opdorp, Aug 11 '11 at 10:53

score 0 · Answer 3 · answered Aug 11 '11 at 10:54

0

It depends on how you get the data from MySQL into PHP, but if you use a funcion like mysql_fetch_array(), you're value in PHP will be NULL as well:

if ([value where id = id] !== null) {
    Twitter: @Twitter;

answered Aug 11 '11 at 10:54

Oscar

65
6

Check if value is null, if it is , print nothing, else, print value. Help?

3 Answers3