create table Rate(
  id int not null,
  code varchar(50) not null,
  date date not null,
  value float not null
);

insert into rate (id, code, date, value) values (1,'EUR','20090605', 1.149); 
insert into rate (id, code, date, value) values (2,'EUR','20090615', 1.161) ;
insert into rate (id, code, date, value) values (3,'EUR','20090617', 1.177) ;
insert into rate (id, code, date, value) values (4,'USD','20090605', 1.625) ;
insert into rate (id, code, date, value) values (5,'USD','20090615', 1.639) ;
insert into rate (id, code, date, value) values (6,'USD','20090617', 1.644);

/* 
    Необходимо сгенерировать календарь по рабочим дням, поместить в таблицу 
    Calendar за период c 05.06.2009 по 18.06.2009.
*/
create table Calendar ( 
  code varchar(50) not null,
  dDay date not null, 
  value varchar(50) not null,
  weekday varchar(50) not null
);
-- insert into Calendar (code, dDay, value,weekday) values 
-- ('EUR','2009-06-05','1.149','Friday'),
-- ('EUR','2009-06-08','1.149','Monday'),
-- ('EUR','2009-06-09','1.149','Tuesday'),
-- ('EUR','2009-06-10','1.149','Wednesday'),
-- ('EUR','2009-06-11','1.149','Thursday'),
-- ('EUR','2009-06-15','1.161','Monday'),
-- ('EUR','2009-06-16','1.161','Tuesday'),
-- ('EUR','2009-06-17','1.177','Wednesday'),
-- ('EUR','2009-06-18','1.177','Thursday'),
-- ('EUR','2009-06-19','1.177','Friday'),
-- ('USD','2009-06-03','1.625','Wednesday'),
-- ('USD','2009-06-04','1.625','Thursday'),
-- ('USD','2009-06-05','1.625','Friday'),
-- ('USD','2009-06-08','1.625','Monday'),
-- ('USD','2009-06-09','1.625','Tuesday'),
-- ('USD','2009-06-10','1.625','Wednesday'),
-- ('USD','2009-06-12','1.639','Thursday'),
-- ('USD','2009-06-15','1.639','Monday'),
-- ('USD','2009-06-16','1.639','Tuesday'),
-- ('USD','2009-06-17','1.644','Wednesday'),
-- ('USD','2009-06-18','1.644','Thursday');
-- ('USD','2009-06-19','1.644','Friday');

/*  
    Вывести значение курса по каждой валюте за каждый день периода 
    с c 05.06.2009 по 18.06.2009 по каждой валюте.
*/
select * from Calendar WHERE dDay between '2009-06-05' and  '2009-06-18';

-- select * from rate;

select *, extract(dow FROM date) as weekid,
          case when extract(dow FROM date) = 1 then 'Monday'
          when extract(dow FROM date) = 2 then 'Tuesday'
          when extract(dow FROM date) = 3 then 'Wednesday'
          when extract(dow FROM date) = 4 then 'Thursday'
          when extract(dow FROM date) = 5 then 'Friday'
          when extract(dow FROM date) = 6 then 'Saturday'
          when extract(dow FROM date) = 0 then 'Sunday'
          
          else null end as WeekName

from ( select date::date from generate_series('2009-06-05',
  '2009-06-18', '1 day'::interval) date ) i
  -- right join (values) days on days.id=
WHERE extract(dow FROM date) NOT IN (0, 6)

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About PostgreSQL

PostgreSQL is a open source relational database system and is also knows as Postgres.

Key Features:

  • Postgres is not only free and open-source but also it is highly extensible.
  • Custom Data types and funtions from various programming languaues can be introduced and the good part is compiling entire database is not required.
  • ACID(Atomicity, Consistency, Isolation, Durability) compliant.
  • First DBMS which implemented Multi-version concurrency control (MVCC) feature.
  • It's the default database server for MacOS.
  • It supports all major operating systems like Linux, Windows, OpenBSD,FreeBSD etc.

Syntax help

1. CREATE

CREATE command is used to create a table, schema or an index.

Syntax:

         CREATE TABLE table_name (
                column1 datatype,
                column2 datatype,
                ....);

2. ALTER

ALTER command is used to add, modify or delete columns or constraints from the database table.

Syntax

ALTER TABLE Table_name ADD column_name datatype;

3. TRUNCATE:

TRUNCATE command is used to delete the data present in the table but this will not delete the table.

Syntax

TRUNCATE table table_name;

4. DROP

DROP command is used to delete the table along with its data.

Syntax

DROP TABLE table_name;

5. RENAME

RENAME command is used to rename the table name.

Syntax

ALTER TABLE table_name1 RENAME to new_table_name1;

6. INSERT

INSERT Statement is used to insert new records into the database table.

Syntax

INSERT INTO table_name (column1, column2, column3, ...) VALUES (value1, value2, value3, ...);

7. SELECT

Select statement is used to select data from database tables.

Syntax:

SELECT column1, column2, ...
FROM table_name;

8. UPDATE

UPDATE statement is used to modify the existing values of records present in the database table.

Syntax

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

9. DELETE

DELETE statement is used to delete the existing records present in the database table.

Syntax

DELETE FROM table_name where condition;