How to insert zero or empty string into a MySQL column defined as NOT NULL?

Declaring a column as "NOT NULL" means that the column does not accept NULL values, but does accept zero (0), and the empty string itself is a value. So, if we want to insert zero or empty string into a MySQL column defined as NOT NULL, there will be no problem. This will become clear by comparing 0 and the empty string with NULL -

mysql> Select 0 IS NULL, 0 IS NOT NULL;
+-----------+---------------+
| 0 IS NULL | 0 IS NOT NULL |
+-----------+---------------+
|         0 |             1 |
+-----------+---------------+
1 row in set (0.00 sec)

The above result set shows that zero (0) is not NULL. This means that zero (0) is itself a value, since we know that NULL means no value.

mysql> Select '' IS NULL, '' IS NOT NULL;
+------------+----------------+
| '' IS NULL | '' IS NOT NULL |
+------------+----------------+
|          0 |              1 |
+------------+----------------+
1 row in set (0.00 sec)

The above result set shows that the empty string (‘’) is not NULL. This means that the empty string ('') is itself a value, since we know that NULL means no value.

Example

mysql> create table test(id int NOT NULL, Name Varchar(10));
Query OK, 0 rows affected (0.19 sec)

mysql> Insert into test6(id, name) values('1', 'Gaurav'),('0','Rahul'),('','Aarav');
Query OK, 3 rows affected, 1 warning (0.08 sec)
Records: 3 Duplicates: 0 Warnings: 1

Warning (Code 1366): Incorrect integer value: '' for column 'id' at row 3

mysql> Select * from test;
+----+--------+
| id | Name |
+----+--------+
|  1 | Gaurav |
|  0 | Rahul  |
|  0 | Aarav  |
+----+--------+
3 rows in set (0.00 sec)

As can be seen from the above result set, we can insert zero (0) an empty string ("") into a statement declared NOT NULL in the column.

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