What is the use of DEFAULT constraint? How can it be applied to a column while creating a table?

DEFAULT constraint is used set a default value for a column in MySQL table. If it is applied on a column then it will take the default value of not giving any value for that column. Its syntax would be as follows −

Syntax

DEFAULT default_value

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

Example

The query below will create a table named workers where we assign the column id a DEFAULT value 1000.

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)

The above result set stores the default value 1000 for id when we do not give any value for the same.

Ankith Reddy

Published on 19-Feb-2018 06:25:07

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