Function to Make Empty String NULL for MySQL Insertion in PHP

Question

This is similar question to MySQL and PHP - insert NULL rather than empty string but I'm still encountering the problem.

I'm trying to create a function so that an empty string is inserted as a NULL into MySQL.

I create the function IsEmptyString:

function IsEmptyString($val){
    if (trim($val) === ''){$val = "NULL";}
}

Before inserting the the variable, I escape it and then I call the function above. I've also tried $val = NULL;

What am I doing wrong? Also should I call the function before escaping?

score 2 · Accepted Answer · answered Oct 13 '11 at 14:15

2

You need to return $val at the end of the function:

function IsEmptyString($val){
    if (trim($val) === ''){$val = "NULL";}
    return $val;
}

answered Oct 13 '11 at 14:15

psx

I tried that but have the same problem. Can I just call the function, e.g. `IsEmptyString($name)` or do I have to set `$name = IsEmptyString($name)`. – Kamil Sindi Oct 13 '11 at 14:17
You need to call $name = IsEmptyString($name). Another option is to define the function as: function IsEmptyString(&$val) then you do not need to return the value – psx Oct 13 '11 at 14:18

score 0 · Answer 2 · answered Oct 17 '16 at 14:05

0

Looks like a good candidate for a ternary operator:

function valOrNull($val) {
    return (trim($val) === '') ? NULL : $val;
}

answered Oct 17 '16 at 14:05

Nathan Arthur

score 0 · Answer 3 · answered Oct 13 '11 at 14:16

You're not returning the value. This should work

function IsEmptyString($val){
    if (trim($val) === ''){$val = "NULL";}
return $val;
}

Also you're assigning your variable to a string and not null.

This line $val = "NULL";

should be

$val = null;

Also see PHP's isset() and empty() functions.

martinstoeckli · Answer 4 · 2011-10-13T14:36:48.690

0

Either you can return the result with return...

function IsEmptyString($val)
{
  if (trim($val) === '')
    return 'NULL';
  else
    return $val;
}

...or you have to pass the variable as reference (note the & before the $val)

function IsEmptyString(&$val)
{
  if (trim($val) === '')
    $val = 'NULL';
}

edited Oct 13 '11 at 14:36

answered Oct 13 '11 at 14:18

martinstoeckli

@Rufinus - It seems that the OP is using the string 'NULL' to build an SQL statement. The function is a modification of the given example, it has other flaws too, as a misleading name for example. – martinstoeckli Nov 12 '15 at 08:07

score 0 · Answer 5 · answered Oct 13 '11 at 14:19

0

alternativly, you can pass val as reference.

function IsEmptyString(&$val){
    if (trim($val) === ''){$val = "NULL";}
}

however, be carefull not to send "'".$val."'" to the database;

answered Oct 13 '11 at 14:19

roselan

5 Answers5