Exam 70-461 topic 1 question 106 discussion

DRAG DROP -
You use Microsoft SQL Server to develop a database that has two tables named Div1Cust and Div2Cust.
Each table has columns named DivisionID and CustomerID.
You need to write a query that meets the following requirements:
✑ The rows in Div1Cust must be combined with the rows in Div2Cust.
✑ The result set must have columns named Division and Customer.
✑ Duplicates must be not retained.
Which three Transact-SQL statements should you use? (To answer, move the appropriate statements from the list of statements to the answer area and arrange them in the correct order.)
Select and Place:

Suggested Answer:
The UNION ALL command is equal to the UNION command, except that UNION ALL selects all values.
The difference between Union and Union all is that Union all will not eliminate duplicate rows, instead it just pulls all rows from all tables fitting your query specifics and combines them into a table.
We should also use the DISTINCT keyword in the third SELECT statement.
Incorrect: The UNION command is used to select related information from two tables, much like the JOIN command. However, when using the UNION command all selected columns need to be of the same data type. With UNION, only distinct values are selected.
References:
https://blog.sqlauthority.com/2009/03/11/sql-server-difference-between-union-vs-union-all-optimal-performance-comparison/