how to make primary key in postgresql code example

Example 1: postgresql drop primary key constraint

alter table public.test1 drop constraint test1_pkey

Example 2: postgres alter table add primary key

-- To set a column as primary key:
ALTER TABLE distributors ADD PRIMARY KEY (tablename);

Example 3: create table postgresql primary key

CREATE TABLE TABLE (
	column_1 data_type PRIMARY KEY,
	column_2 data_type,
	…
);