psql 

База данных и таблица
~~~~~~~~~~~~~~~~~~~~~


        => create database db8;
        CREATE DATABASE

        => \c db8
        You are now connected to database "db8" as user "postgres".

        => create table observations(
        =>   date_taken date not null,
        =>   temp numeric check( temp between -60 and 60 )
        => );
        CREATE TABLE

Добавление записей и проверка ограничений
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


        => insert into observations values (current_date, 25), (current_date-1, 22);
        INSERT 0 2

        => insert into observations values (current_date, 70);
        ERROR:  new row for relation "observations" violates check constraint "observations_temp_check"
        DETAIL:  Failing row contains (2016-06-16, 70).

        => insert into observations values (null, 20);
        ERROR:  null value in column "date_taken" violates not-null constraint
        DETAIL:  Failing row contains (null, 20).

Представление
~~~~~~~~~~~~~


        => create view observ_fahrenheit as
        =>   select date_taken, temp as celsius, round(temp*5/9+32) as fahrenheit from observations;
        CREATE VIEW

        => select * from observ_fahrenheit;
         date_taken | celsius | fahrenheit 
        ------------+---------+------------
         2016-06-16 |      25 |         46
         2016-06-15 |      22 |         44
        (2 rows)
        

Индекс
~~~~~~


        => create index observations_date on observations(date_taken);
        CREATE INDEX

        => \q