dbms

CREATE TABLE IF NOT EXISTS test_tab (
    id SERIAL PRIMARY KEY,          
    surname VARCHAR(50),           
    name VARCHAR(50),              
    age INT CHECK (age >= 0),      
    height NUMERIC(5, 2)         
);

ALTER TABLE test_tab
DROP COLUMN IF EXISTS surname,
DROP COLUMN IF EXISTS name;

ALTER TABLE test_tab
ADD COLUMN name_surname VARCHAR(100); 

INSERT INTO test_tab (age, height, name_surname)
VALUES
(25, 175.50, 'John Doe'),
(30, 180.00, 'Jane Smith'),
(22, 165.75, 'Alice Johnson'),
(29, 170.25, 'Bob Brown'),
(35, 168.50, 'Charlie Davis');

select * from test_tab