Easy Tutorial
Sqlite Alias Sqlite Like Clause Sqlite Syntax Sqlite Php Sqlite Distinct Keyword Sqlite Functions Sqlite Autoincrement Sqlite Detach Database Sqlite Unions Clause Sqlite Attach Database Sqlite Joins Sqlite Pragma Sqlite Group By Sqlite Where Clause Sqlite Injection Sqlite And Or Clauses Sqlite Operators Sqlite Constraints Sqlite Drop Table Sqlite C Cpp Sqlite Order By Sqlite Subquery Sqlite Expressions Sqlite View Sqlite Indexed By Sqlite Alter Command Sqlite Insert Sqlite Select Sqlite Explain Sqlite Python Sqlite Installation Sqlite Transaction Sqlite Update Sqlite Delete Sqlite Commands Sqlite Date Time Sqlite Null Values Sqlite Create Table Sqlite Java Sqlite Data Types Sqlite Trigger Sqlite Create Database Sqlite Limit Clause Sqlite Intro Sqlite Truncate Table Sqlite Vacuum Sqlite Perl Sqlite Glob Clause Sqlite Index Sqlite Tutorial Sqlite Having Clause
❮ Sqlite Date Time Sqlite Create Table ❯

SQLite NULL Values

In SQLite, NULL is used to represent a missing entry. A NULL value in a table is a value that appears as a blank in the field.

A field with a NULL value is a field without a value. It is crucial to understand that a NULL value is different from zero or a field containing spaces.

Syntax

The basic syntax for using NULL when creating a table is as follows:

SQLite> CREATE TABLE COMPANY(
   ID INT PRIMARY KEY     NOT NULL,
   NAME           TEXT    NOT NULL,
   AGE            INT     NOT NULL,
   ADDRESS        CHAR(50),
   SALARY         REAL
);

Here, NOT NULL indicates that the column always accepts an explicit value of the given data type. There are two columns where we did not use NOT NULL, meaning these columns can be NULL.

A field with a NULL value can be left empty during record creation.

Example

NULL values can cause issues when selecting data because when comparing an unknown value with another value, the result is always unknown and will not be included in the final results. Suppose we have the following records in the COMPANY table:

ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
1           Paul        32          California  20000.0
2           Allen       25          Texas       15000.0
3           Teddy       23          Norway      20000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0
6           Kim         22          South-Hall  45000.0
7           James       24          Houston     10000.0

Let's use the UPDATE statement to set some nullable values to NULL, as shown below:

sqlite> UPDATE COMPANY SET ADDRESS = NULL, SALARY = NULL where ID IN(6,7);

Now, the records in the COMPANY table appear as follows:

ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
1           Paul        32          California  20000.0
2           Allen       25          Texas       15000.0
3           Teddy       23          Norway      20000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0
6           Kim         22
7           James       24

Next, let's look at the usage of the IS NOT NULL operator, which is used to list all records where SALARY is not NULL:

sqlite> SELECT  ID, NAME, AGE, ADDRESS, SALARY
        FROM COMPANY
        WHERE SALARY IS NOT NULL;

The above SQLite statement will produce the following result:

ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
1           Paul        32          California  20000.0
2           Allen       25          Texas       15000.0
3           Teddy       23          Norway      20000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0

The following demonstrates the usage of the **IS NULL** operator, which lists all records where SALARY is NULL:

sqlite> SELECT ID, NAME, AGE, ADDRESS, SALARY FROM COMPANY WHERE SALARY IS NULL;


The above SQLite statement will produce the following result:

ID NAME AGE ADDRESS SALARY

6 Kim 22 7 James 24 ```

❮ Sqlite Date Time Sqlite Create Table ❯