Unions Explained

This guide will explain the basic outcome of preforming a data union.

• A union is used to concatenate data sets into one unified set. 
• A union is done expecting the column headers to be almost identical in both datasets.   
  • If a union is done and one dataset has additional columns the column will add Null values to the second dataset 
  • The columns must have identical names in all data sets for a proper union. For example "column 1" and "column_1" will be viewed as two distinct columns and will be added separately.
  • Be aware that unions not join the data in anyway, which is why the two rows with the ID "4" stay separate in this union.
    
    
    

  Original Datasets

  Database A				Database B
  ID	Fruit	Taste Rating		ID	Vegetable	Taste Rating
  1	Apple	7		4	Lettuce	4
  2	Pear	6		5	Carrot	7
  3	Orange	6		6	Celery	6
  4	Lemon	4		7	Broccoli	8

  Union-ed Dataset

   

  Database Union
  ID	Fruit	Vegetable	Taste Rating
  1	Apple	Null	7
  2	Pear	Null	6
  3	Orange	Null	6
  4	Lemon	Null	4
  4	Null	Lettuce	4
  5	Null	Carrot	7
  6	Null	Celery	6
  7	Null	Broccoli	8

   

   

   

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