Add a positive integer constraint to an integer column in MySQL?

You need to use unsigned for this because it won’t allow you to enter a negative number.

The syntax is as follows

CREATE TABLE yourTableName
(
   yourColumnName INT UNSIGNED
);

To understand the concept, let us create a table. The query to create a table is as follows

mysql> create table OnlyPositiveValue
   - > (
   - > Marks int UNSIGNED
   - > );
Query OK, 0 rows affected (0.58 sec)

Before inserting data in the table, use the below query.

The query is as follows

mysql> SET @@SESSION.sql_mode = 'STRICT_TRANS_TABLES';
Query OK, 0 rows affected, 1 warning (0.00 sec)

Now if you will add a negative number in the INSERT command, the following error would be visible

mysql> insert into OnlyPositiveValue values(-10);
ERROR 1264 (22003): Out of range value for column 'Marks' at row 1
mysql> insert into OnlyPositiveValue values(-100);
ERROR 1264 (22003): Out of range value for column 'Marks' at row 1

Let us insert positive numbers.

The query is as follows

mysql> insert into OnlyPositiveValue values(0);
Query OK, 1 row affected (0.17 sec)
mysql> insert into OnlyPositiveValue values(10);
Query OK, 1 row affected (0.14 sec)
mysql> insert into OnlyPositiveValue values(100);
Query OK, 1 row affected (0.11 sec)

Display all records from the table using select statement.

The query is as follows

mysql> select *from OnlyPositiveValue;

The following is the output displaying positive numbers

+-------+
| Marks |
+-------+
|     0 |
|    10 |
|   100 |
+-------+
3 rows in set (0.00 sec)