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 |