MySQL get all unique values between two columns

问题

I have a table with two columns that contain ID's. I want to query the table to show one list of each ID from the two columns.

TABLE
A | B
-----
1 | 2
2 | 3
5 | 4
6 | 2

I want the result to be:

TABLE
  A
  -
  1
  2
  3
  5
  4
  6

回答1:

Use the UNION operator

SELECT A FROM TABLE
UNION
SELECT B FROM TABLE

来源：https://stackoverflow.com/questions/22976395/mysql-get-all-unique-values-between-two-columns