Primary keys are for relating to other records in other tables. Creating an "intelligent" primary key is going to be a pain to manage. Why can you not use a...

You could use EXISTS, LEFT JOIN... what did you try?

Looks like this worked...
use tempdb;
GO

CREATE TABLE PayDates(PayDate DATE PRIMARY KEY);
GO
INSERT INTO PayDates(PayDate) VALUES ('01/02/2018'),('02/02/2018'),('3/02/2018');

CREATE TABLE Acct(account int, amt int, rnk...

SET [field] = CAST....

'dual' is a table in Oracle.  Are you using Oracle as your source or SQL Server?

Your syntax for CAST is wrong.
It's CAST(expression AS datatype)

for example...

SELECT 'The film, '+ Title + ' is ' + CAST(RunTimeMinutes AS VARCHAR(3)) +...

Use LAG() 
https://docs.microsoft.com/en-us/sql/t-sql/functions/lag-transact-sql

WHERE [SaleDate]>DATEADD("m",-3,GETDATE()) ?
https://docs.microsoft.com/en-us/sql/t-sql/functions/dateadd-transact-sql

Like this?

SELECT YrMo
    , OType
    , Orders
    , Total
FROM
(SELECT '13/03'AS YrMo
    , 'Sales Order' AS OType
    , 300 AS Orders
    , 15000 AS Total

Agreed. Doesn't sound terribly complicated given a proper description of what data you start with and the output desired...

What do "a", "b", "c" represent? Actual values or first value, second value, third value?

Write a query to get the below result. I need output as below

what happened when you tested the code provided by deepika0928?
What exactly is the point of your post? It's just a bunch of random-ish code... Did you try any of...

Makes me think the OP is thinking in terms of Oracle, which can do that...

People here are more than happy to help, but you have to do your homework first. If you don't at least try to solve the problem yourself (post what you...