--for and while loop implementation

--Basic For Loop to check if inputted number is prime or not
-- Create Function PrimeNumber(n integer)
-- Returns varchar
-- LANGUAGE PLPGSQL as 
-- $$
-- Declare 
-- status integer;
-- Begin
--   status:=0;
--   for i in 2 ..(n/2) loop
--     if n%i = 0 then
--       status = 1;
--       EXIT;
--     End if;
--   End loop;
--   if status = 0 then
--     return 'Prime Number';
--   else
--     return 'Not Prime Number';
--   End if;
-- End;
-- $$;

-- Select PrimeNumber(100);
-- Select PrimeNumber(17);
---------------------------------------------------------------------------
-- CREATE FUNCTION is_prime(num INT)
-- RETURNS BOOLEAN 
-- LANGUAGE PLPGSQL as
-- $$
-- DECLARE
--     i INT;
-- BEGIN
--   if num <= 1 then
--     return false;
--   End if;
--   for i in 2..(num/2) loop
--     if num%i = 0 then
--       return false;
--     End if;
--   End loop;
-- return True;
-- END;
-- $$;

-- Select is_prime(17);

-- Create Function PrimeNumberList (n integer)
-- Returns json
-- LANGUAGE PLPGSQL as
-- $$
-- Declare 
-- P_Json json;
-- BEGIN
-- P_Json:= '{}'::jsonb;
--   for i in 1..n loop
--     if is_prime(i) then
--       P_Json := jsonb_insert(P_Json, '{0}', i::integer);
--     End if;
--   End loop;
-- return P_Json;
-- End;
-- $$;
---------------------------------------------------------------------------------------
-- CREATE FUNCTION PrimeNumberList(num INT)
-- RETURNS jsonb
-- LANGUAGE PLPGSQL as
-- $$
-- DECLARE
-- i INT;
-- j INT;
-- P_Json jsonb;
-- BEGIN
--   P_Json:= '{}'::jsonb;
  
--   for i in 1..num loop
--     for j in 2..(i/2) loop
--       if i%j = 1 then 
--         P_Json := jsonb_insert(P_Json, '{0}', i);
--       End if;
--     End Loop;
--   End Loop;
  
-- return P_Json;
-- END;
-- $$;

-- Select PrimeNumberList(30);

-- SELECT jsonb_insert('[1,2,3]', '{0}', '0');

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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;