SQL UNION

QL UNION is query that allows you to select related information from 2 tables, this is combine 2 SELECT statement into 1 and display it out.

UNION will only return DISTINCT value only. Which means will eliminate duplicate records that returned.

There are some condition that need to meet when using the UNION statement.
First SELECT statement must have the same column number if compare with 2nd SELECTStatement.
Data type also has to be same for both columns to combine.

The syntax is as follows:

SELECT [COLUMN NAME 1], [COLUMN NAME 2],… FROM [TABLE NAME 1]
UNION
SELECT [COLUMN NAME 1], [COLUMN NAME 2],… FROM [TABLE NAME 2]

EXAMPLE :

We have 2 table name GamesScores, GameScores_new.

Table GameScores

PlayerName	Department	Scores
Jason	IT	3000
Irene	IT	1500
Jane	Marketing	1000
David	Marketing	2500
Paul	HR	2000
James	HR	2000

Table GameScores_new

PlayerName	Department	Scores
Jason	IT	3000
David	Marketing	2500
Paul	HR	2000
James	HR	2000

SQL statement :

SELECT PlayerName FROM GameScores
UNION
SELECT PlayerName FROM GameScores_new

Result:

PlayerName

David

Irene

James

Jane

Jason

Paul