Get the highest/lowest value from 2 columns - sql

Question

I've got this table:
BP1 BP2
-----------------------------
140 80
153 88
90 162
98 214
98 69
I want to organize it into 2 columns: one of high BP and other of low BP:
Expected output:
BP_High BP_Low
---------------------------------
140 80
153 88
162 90
214 98
98 69
*all values are int
I've tried:
SELECT CASE WHEN BP1 > BP2 THEN BP1
WHEN BP1 < BP2 THEN BP2 END BP_High,
CASE WHEN BP1 > BP2 THEN BP2
WHEN BP1 < BP2 THEN BP1 END BP_Low
FROM Table
and it does not work...it gives me all mixed up:
BP_High BP_Low
---------------------------------
140 80
153 88
90 162
98 214
98 69
I've also tried:
SELECT CASE WHEN BP1 > BP2 THEN BP1
ELSE BP2 END BP_High,
CASE WHEN BP1 > BP2 THEN BP2
ELSE BP1 END BP_Low
FROM Table
Is there any other way then CASE WHEN to in order to get the highest/lowest value from 2 columns?

Answer 1

Your third attempt is almost correct, and you in fact can use CASE expressions here:
SELECT
CASE WHEN BP1 > BP2 THEN BP1 ELSE BP2 END AS BP_High,
CASE WHEN BP1 < BP2 THEN BP1 ELSE BP2 END AS BP_Low
FROM yourTable;
On other databases, such as MySQL, Postgres, or SQLite, there are LEAST() and GREATEST() scalar functions available. On those databases, your query can be simplified to:
SELECT
GREATEST(BP1, BP2) AS BP_High,
LEAST(BP1, BP2) AS BP_Low
FROM yourTable;