Question

I have 2 tables:

One is Promotion

| PromoId |Promo Decription|
----------------------
|   101   |  abc|
|   102   |  pqr|
|   103   |  alp|
|   104   |  adc|
|   201   |  abc|

and the other is PromotionType

| PromoId | PromoType  | 
----------------------
|   101   |  1   |  
|   121   | 2    |  
|   188   | 3    |  
|   104   | 4    |  
|   191   | 4    |  
|   102   | 4    | 

I want a resultant table

| PromoId | Flag |Promo Decription |PromoType  |    
----------------------
|   101   |  1   |                 | 1 |
|   121   | 0    |                 | 2 | 
|   188   | 0    |                 | 3 | 
|   104   | 1    |  adc            | 4 |  
|   191   | 0    |                 | 4 |  
|   102   | 1    |  pqr            | 4 | 
|   103   | 1    |  alp            |   |
|   201   | 0    |  abc            |   |

i.e I want a resultant table , which is the union of two tables .It should not contain duplicate values and the value of flag is set to true for all the values of PromoId’s which are common to both tables.

I am using Sql Server as our database.

Answer 1

You can use a FULL OUTER JOIN to perform this:

select 
  coalesce(p.promoid, t.promoid) promoid,
  case when p.promoid = t.promoid then 1 else 0 end flag
from promotion p
full outer join promotiontype t
  on p.promoid = t.promoid
order by promoid

See SQL Fiddle with Demo

Result:

| PROMOID | FLAG |
------------------
|     101 |    1 |
|     102 |    1 |
|     103 |    0 |
|     104 |    1 |
|     121 |    0 |
|     188 |    0 |
|     191 |    0 |
|     201 |    0 |

Edit, even with your changes to the data sample the query will still produce the result:

select 
  coalesce(p.promoid, t.promoid) promoid,
  case when p.promoid = t.promoid then 1 else 0 end flag,
  isnull(p.[Promo Decription], '') [Promo Decription],
  isnull(t.PromoType, null) PromoType
from promotion p
full outer join promotiontype t
  on p.promoid = t.promoid
order by 
  case when PromoType is not null then 0 else 1 end, promotype, promoid

See SQL Fiddle with Demo

Result is:

| PROMOID | FLAG | PROMO DECRIPTION | PROMOTYPE |
-------------------------------------------------
|     101 |    1 |              abc |         1 |
|     121 |    0 |                  |         2 |
|     188 |    0 |                  |         3 |
|     102 |    1 |              pqr |         4 |
|     104 |    1 |              adc |         4 |
|     191 |    0 |                  |         4 |
|     103 |    0 |              alp |    (null) |
|     201 |    0 |              abc |    (null) |