text: -- 1. Create database called «lab1»
  CREATE DATABASE lab1;
  -- 2. Create table «users» with following fields
  -- • id (autoincrementing integer)
  -- • firstname (string max length 50)
  -- • lastname (string max length 50)
  CREATE TABLE users
  (
      id        SERIAL,
      firstname VARCHAR(50),
      lastname  VARCHAR(50)
  );
  -- 3. Add integer column (0 or 1) «isadmin» to «users» table
  ALTER TABLE users
      ADD COLUMN isadmin INTEGER
          CONSTRAINT checker CHECK (isadmin = 0 OR isadmin = 1);
  -- 4. Change type of «isadmin» column to boolean
  ALTER TABLE users
      ALTER COLUMN isadmin SET DATA TYPE BOOLEAN USING users.isadmin::bool;
  -- 5. Set default value as false to «isadmin» column
  ALTER TABLE users
      ALTER COLUMN isadmin SET DEFAULT false;
  -- 6. Add primary key constraint to id column
  ALTER TABLE users
      ADD PRIMARY KEY (id);
  -- 7. Create table «tasks» with following fields • id (autoincrementing integer)
  -- • name (string max length 50)
  -- • user_id (integer)
  CREATE TABLE tasks
  (
      id      SERIAL,
      name    VARCHAR(50),
      user_id INTEGER
  );
  -- 8. Delete «tasks» table
  DROP TABLE tasks RESTRICT;
  -- 9. Delete «lab1» database
  DROP DATABASE lab1;
  