What does the default constraint do? How do I apply this to the columns when creating the table?

DEFAULT constraint is used to set default values ​​for columns in MySQL tables. If applied to a column, the column will take on the default value, i.e. no value will be assigned to the column. Its syntax is as follows −

Syntax

DEFAULT default_value

Here, default_value is the default value set for the column.

Example

The following query will create a table called workers where we assign a default value of 1000 to the column id.

mysql> Create table workers(Name Varchar(25), Id INT NOT NULL DEFAULT 1000);
Query OK, 0 rows affected (0.47 sec)

mysql> Insert into workers(Name, Id) values('Ram', 101);
Query OK, 1 row affected (0.04 sec)

mysql> Insert into workers(Name) values('Mohan');
Query OK, 1 row affected (0.10 sec)

mysql> Select * from Workers;

+-------+------+
| Name  | Id   |
+-------+------+
| Ram   | 101  |
| Mohan | 1000 |
+-------+------+

2 rows in set (0.00 sec)

When we do not provide any value for the id, the above result set will store the default value of 1000.

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