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

What attribute makes the input text box to not be modified by the user?
checked="checked" readonly="readonly" disabled="disabled"
<input type="text" value="fixed-value" readonly="readonly" name="a_name" />
What CSS property allows you to create rounded corners in your webpage design?
background-size border-size border-radius
.class {
  border:2px solid blue;
What instruction displays a confirmation dialog box to the viewer, who must then click OK or Cancel to proceed?
indexOf() confirm() prompt()
var ques = window.confirm("The result of 0+0 is 0?");
if (ques) alert("Corect");
else alert("Incorrect");
Indicate the PHP function that returns the lowest number of the parameter values.
floor() ceil() min()
$min_nr = min(12, 8, 25, 13);
echo $min_nr;        // 8
Insert, Select and Update NULL value in MySQL

Last accessed pages

  1. JavaScript Chronometer / Stopwatch (591)
  2. PHP MySQL - INSERT INTO (1690)
  3. jQuery Ajax - load() method (2056)
  4. PHP-MySQL Tutorials (376)
  5. PHP-MySQL free course, online tutorials PHP MySQL code (7509)

Top accessed pages

  1. PHP-MySQL free course, online tutorials PHP MySQL code (7509)
  2. Courses Web: PHP-MySQL JavaScript Ajax HTML CSS Flash-AS3 (7242)
  3. Get Attribute (ID, Class, Name, Title, Src) with jQuery (6959)
  4. PHP Chat Script (6437)
  5. PHP PDO - exec (INSERT, UPDATE, DELETE) MySQL (6417)