In this tutorial you can learn how to work with NULL in MySQL tables: Insert, Update, and Select columns with NULL value.

Add column with NULL value

To insert into a MySQL table rows with columns having NULL, add the NULL value without quotes.
$sql = "INSERT INTO `table_name`
 (`column1`, `column2`, `column3`)
 ('val1', NULL, 'val3')";

Or, if the NULL value is stored into a variable, add "NULL" as a string to that variable, then write the variable into the SQL query, without quotes.
$nul = 'NULL';
$sql = "INSERT INTO `table_name`
 (`column1`, `column2`, `column3`)
 ('val1', $nul, 'val3')";

- If you create the $nul value like this:   $nul = NULL; , the SQL query will contain nothing in the place where this variable is added. Will result:
INSERT INTO `table_name` (`column1`, `column2`, `column3`) VALUES ('val1', , 'val3')

- If you want to insert the string "NULL", add it within quotes:
$sql = "INSERT INTO `table_name`
 (`column1`, `column2`, `column3`)
 ('val1', 'NULL', 'val3')";

UPDATE with NULL value

The same works with UPDATE.
$sql = "UPDATE `table_name` SET `column1`='val1', `column2`=NULL, WHERE `column3`='val3'";
$nul = 'NULL';
$sql = "UPDATE `table_name` SET `column1`='val1', `column2`=$nul, WHERE `column3`='val3'";

SELECT fields with NULL value

To select rows in a MySQL table according to columns with NULL value, use IS NULL.
$sql = "SELECT * FROM `table_name` WHERE `column` IS NULL";

If you want to Not return the rows with a specific NULL field, use IS NOT NULL.
$sql = "SELECT * FROM `table_name` WHERE `column` IS NOT NULL";

Daily Test with Code Example

Which tag can be used to create input text field in web page?
<form> <input> <div>
<input type="text" name="a_name" value="val" />
Which CSS property displays the text in a small-caps font?
display font-variant font-style
h3 {
  font-variant: small-caps;
What instruction displays a notice box with a message inside it, in JavaScript?
for() Date() alert()
var msg = "Visit";
Indicate the PHP code used to get the users IP.
echo $ip;
Insert, Select and Update NULL value in MySQL

Last accessed pages

  1. Ajax-PHP Rating Stars Script (7832)
  2. Get the value of the selected /checked checkboxes in a form (14782)
  3. Ajax-PHP Chat Script (20135)
  4. AJAX Course, free Lessons (3885)
  5. jQuery Ajax - load() method (6069)

Top accessed pages

  1. Courses Web: PHP-MySQL JavaScript Ajax HTML CSS Flash-AS3 (31820)
  2. PHP-MySQL free course, online tutorials PHP MySQL code (25967)
  3. Get Attribute (ID, Class, Name, Title, Src) with jQuery (24874)
  4. Read Excel file data in PHP - PhpExcelReader (24069)
  5. PHP PDO - exec (INSERT, UPDATE, DELETE) MySQL (21680)