postgresql: how to define a JSONB column with default value

Question

I am unable to find in the documentation how to create a JSONB column in PostgreSQL that has a DEFAULT value of an empty json document.

How the above can be stated in the CREATE TABLE definition ?

• Jasen: what's an empty json document? "" contrains a string {} contains an object null contains a null ?

Answer 1

That's the same as with any other default value:

create table amsterdam
(
 id integer primary key, 
 payload jsonb not null default '{}'::jsonb
);

• Eric: How to set a default value other than {} ? .e.g [1,2,3] ?
• Abhay: How to define default value for jsonb[] ?

Answer 2

If you are altering an already existing table, then the syntax is as follows:

ALTER TABLE my_table ADD COLUMN my_column JSONB NOT NULL DEFAULT '{}'::jsonb;

• mustaccio: How is this different from the existing accepted answer?
• Valery Bugakov: The captain here! alter vs create