The DEFAULT constraint in SQL is used to fill up the mentioned column with default and fixed values. All the new records will have the same value if no other value is mentioned.
- Syntax using DEFAULT Constraint –
CREATE TABLE table_name
(column1 datatype,column2 datatype,.....,
columnN datatype DEFAULT 'value' );
Example – Create an Employee table with columns as (ID, Name, Country) and add constraint on Country as “INDIA”.
CREATE TABLE EMPLOYEES
( ID int NOT NULL,
Emp_Name varchar (50) NOT NULL,
Country varchar(255) DEFAULT 'India');
- Here the EMPLOYEES table has been created with the DEFAULT constraint. Now let’s insert some values into the table.
INSERT INTO EMPLOYEES VALUES(1, 'Simon', DEFAULT);
INSERT INTO EMPLOYEES VALUES(2, 'Maria', DEFAULT);
- Here we haven’t mentioned any Country name, but have a constraint instead of any Country’s name.
Implementing the SELECT Statement to view the EMPLOYEES table –
| ID | Emp_name | Country |
| 1 | Simon | India |
| 2 | Maria | India |
Other SQL topics to check out:
- What is RDBMS (Relational Database Management System)?
- SQL SELECT Statement
- SQL INSERT INTO SELECT Statement
- SQL ALL Operator
- SQL WHERE Clause
- SQL AND Operator
- SQL OR Operator
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