Set or Remove Default Value of a Column in PostgreSQL

To change the default value of column, use SET DEFAULT or DROP DEFAULT clause with ALTER TABLE ALTER COLUMN statement.

Syntax: 

ALTER TABLE <table_name>
ALTER COLUMN <column_name>
[SET DEFAULT <value> | DROP DEFAULT];

Consider that you already have the following employee table.

The following sets the default value of the salary column. So if you insert a record without specifying the value for the salary column, it will store default value in the salary column for that row.

Example: Set Default Value

ALTER TABLE employee
ALTER COLUMN salary
SET DEFAULT 0;

The following reflects the changes in the employee table.

Remove Default Value

To remove default value of the column, use ALTER TABLE ALTER COLUMN statement along with DROP DEFAULT clause, as shown below.

Example: Remove Default Value

ALTER TABLE employee
ALTER COLUMN salary
DROP DEFAULT;

Set Column Default using pgAdmin

You can assign or change the default value of a column in pgAdmin by right clicking on the table and select 'Properties' in the context menu. This will open a popup where you can add or edit multiple columns definition.

In the popup, go to 'Columns' tab and click on the edit icon againt a column to change the default value, as shown below.

Now, go to the 'Constraints' tab and set or change the default value. Click on the Save button to save the changes.