MySQL int column allows null but enters null as zero - php

Question

I've looked around and have noticed a few people have had the same problem but their oversight doesn't seem to apply here.
I have a PHP function to add an array of values into a table. It first checks whether the values are empty and if so replaces them with NULL, in order to place a null in the table field. Each fields that I'm placing null into allows for null yet places a 0 there instead.
Here's some code:
public static function AddGame($array, $tId)
{
global $db; // Bring DB into scope
// Get IDs from particular names
$locId = $array['fLocation'];
// Ensure empty values are SQL null
$hTeamId = "'{$array['fHomeTeam']}'";
$vTeamId = "'{$array['fVisitTeam']}'";
$hScore = "'{$array['fHomeScore']}'";
$vScore = "'{$array['fVisitScore']}'";
$hHoldFor = "'{$array['fHomeHoldFor']}'";
$vHoldFor = "'{$array['fVisitHoldFor']}'";
// Prepare row for insertion
$row = "'','$tId','$locId',$hTeamId,$vTeamId,'{$array['fDate']}','{$array['fTime']}',$hScore,$vScore,'{$array['fGameType']}',$hHoldFor,$vHoldFor";
$stmt = $db->prepare("INSERT INTO `game` VALUES($row)");
if($stmt->execute()) return true;
else return false;
}
I've debugged this function at various lines and have dumped the $row string and it shows this, which is expected:
'','1','1','21','21','10/10/12','10:30AM','NULL','NULL','pool','NULL','NULL'
Yet when I check the table text type fields literally have the value NULL which is not what I want and also int fields show as 0. If I leave the values blank or as PHP's null then text fields show as empty (or properly null as I'd like) yet the ints still show as 0.
I expect this is only caused due to the way I insert the values indirectly.
Here is the SHOW CREATE TABLE game
CREATE TABLE `game` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`tId` int(11) NOT NULL,
`Lid` int(11) NOT NULL,
`hTeamId` int(11) DEFAULT NULL,
`vTeamId` int(11) DEFAULT NULL,
`date` text NOT NULL,
`time` text NOT NULL,
`hScore` int(11) DEFAULT NULL,
`vScore` int(11) DEFAULT NULL,
`type` text NOT NULL,
`hHoldFor` text,
`vHoldFor` text,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=latin1
UPDATE:
INSERT INTO `game` VALUES('','1','1','','','10/09/12','9:30AM','','','pool','winner of pool A','winner of pool B')

Answer 1

You are physically setting the value of the wanted NULL columns to a string of 'NULL'
NULL != 'NULL'
If you set your table structure for those columns to NULL, you can omit them from your query and they will automatically be NULL on insert.
Do this instead:
if(!empty($hHoldFor)) $hHoldFor = $array['fHomeHoldFor'];
Update
I was looking further into your example and there is a second point of failure.
$row = ... ",'$hHoldFor','$vHoldFor'";
The above line, if you set $hHoldFor = NULL, will insert quotes around NULL, turning it back into a string of NULL.
Try this:
if(!empty($hHoldFor)) $hHoldFor = "'{$array['fHomeHoldFor']}'";
...
$row = ... ",$hHoldFor,$vHoldFor";
This removes the single quotes around this value in the QUERY string and adds them to the variable itself.
Update 2
Here is an SQLFiddle using your schema. It returns NULL for NULL columns. Can you do an echo "INSERT INTOgameVALUES($row)"; and post the output? The issue is PHP is converting the NULL to 'NULL' still somewhere. This will help us get to the bottom of it.
Update 3
The issue is just as thought. Your PHP is inserting a blank string, '', into your database, which is not a NULL value. NULL is of a type, '' is a string with no length.
INSERT INTO `game` VALUES('','1','1','','','10/09/12','9:30AM','','','pool','winner of pool A','winner of pool B')
Try this:
public static function AddGame($array, $tId)
{
global $db; // Bring DB into scope
// Get IDs from particular names
$locId = $array['fLocation'];
// Ensure empty values are SQL null
$hTeamId = (strlen($array['fHomeTeam']) != 0 ? "'{$array['fHomeTeam']}'" : 'NULL');
$vTeamId = (strlen($array['fVisitTeam']) != 0 ? "'{$array['fVisitTeam']}'" : 'NULL');
$hScore = (strlen($array['fHomeScore']) != 0 ? "'{$array['fHomeScore']}'" : 'NULL');
$vScore = (strlen($array['fVisitScore']) != 0 ? "'{$array['fVisitScore']}'" : 'NULL');
$hHoldFor = (strlen($array['fHomeHoldFor']) != 0 ? "'{$array['fHomeHoldFor']}'" : 'NULL');
$vHoldFor = (strlen($array['fVisitHoldFor']) != 0 ? "'{$array['fVisitHoldFor']}'" : 'NULL');
// Prepare row for insertion
$row = "'','$tId','$locId',$hTeamId,$vTeamId,{$array['fDate']}','{$array['fTime']}',$hScore,$vScore,'{$array['fGameType']}',$hHoldFor,$vHoldFor";
$stmt = $db->prepare("INSERT INTO `game` VALUES($row)");
if($stmt->execute()) return true;
else return false;
}

Answer 2

You can't insert 'NULL'. Remove the single quotes around NULL.
Your string
'','1','1','21','21','10/10/12','10:30AM','NULL','NULL','pool','NULL','NULL'
Should look like
'','1','1','21','21','10/10/12','10:30AM',NULL,NULL,'pool',NULL,NULL
You should also define a column list whenever making an INSERT (ie. INSERT INTO table (col1, col2) VALUES ...)
Edit 1
I would recommend looking through your SHOW CREATE TABLE tbl_name
Edit 2
After testing this, I would still say the problem is with how you're inserting the data.
(18,1,1,21,21,'10/10/12','10:30AM',NULL,NULL,'pool',NULL,NULL)
Works.
('18','1','1','21','21','10/10/12','10:30AM','NULL','NULL','pool','NULL','NULL')
Does not work: Incorrect integer value: 'NULL' for column 'hScore' at row 1:
Edit 3
Here is an improved version of your class:
public static function AddGame($array, $tId)
{
global $db; // Bring DB into scope
// Get IDs from particular names
$locId = $array['fLocation'];
// Ensure empty values are SQL null
$hTeamId = empty($array['fHomeTeam']) ? 'NULL' : "'" . $array['fHomeTeam'] . "'";
$vTeamId = empty($array['fVisitTeam']) ? 'NULL' : "'" . $array['fVisitTeam'] . "'";
$hScore = empty($array['fHomeScore']) ? 'NULL' : "'" . $array['fHomeScore'] . "'";
$vScore = empty($array['fVisitScore']) ? 'NULL' : "'" . $array['fVisitScore'] . "'";
$hHoldFor = empty($array['fHomeHoldFor']) ? 'NULL' : "'" . $array['fHomeHoldFor'] . "'";
$vHoldFor = empty($array['fVisitHoldFor']) ? 'NULL' : "'" . $array['fVisitHoldFor'] . "'";
// Prepare row for insertion
$row = "$tId,$locId,$hTeamId,$vTeamId,'{$array['fDate']}','{$array['fTime']}',$hScore,$vScore,'{$array['fGameType']}',$hHoldFor,$vHoldFor";
$stmt = $db->prepare("INSERT INTO game (tId, Lid, hTeamId, vTeamId, date, time, hScore, vScore, type, hHoldFor, vHoldFor) VALUES($row)");
if($stmt->execute()) return true;
else return false;
}
Non-NULL values will be encased in quotes, otherwise they are assigned NULL. I've also defined the column list for INSERT and excluded id, as it's an AUTO_INCREMENT column.

Answer 3

Does you column allows NULL values? Check the DDL again maybe you have set the DEFAULT VALUE to zero.
When you try to insert null value in a column, don not wrap it with single quote. Example
INSERT INTO tableName (colName, ColNameB) VALUES (1, NULL)

Answer 4

In my case i had to display three situations: Case-empty, Case-yes and Case-no. I planned to use null, one and zero. But the null was being saved always as 0. The column i was working accepted null entries but all my nulls was being saved as zeros.
My solution, was considering Case-empty as zero, Case-yes as the number one and case-no as the number two. It is a workaround but solved the problem.