UNION vs CASE Statement

SQL
1

In Lecture 13, the solution involved performing UNION on three queries on the customers table.

– Create a report on the customers table showing the
– loyalty type based on the points each customer has.
– points < 2000: Bronze
– points >= 2000 and <= 3000: Silver
– points > 3000: Gold
– Note that the ORDER BY clause should appear in the final
– query only. If placed elsewhere, a syntax error will result

USE sql_store;

SELECT
	CONCAT(c.first_name, " ", c.last_name) AS customer,
    "Bronze" as type
FROM
	customers c
WHERE
	c.points < 2000

UNION

SELECT
	CONCAT(c.first_name, " ", c.last_name) AS customer,
    "Silver" as type
FROM
	customers c
WHERE
	c.points BETWEEN 2000 AND 3000

UNION

SELECT
	CONCAT(c.first_name, " ", c.last_name) AS customer,
    "Gold" as type
FROM
	customers c
WHERE
	c.points > 3000
ORDER BY 
	customer;

-- I wonder if we can generate the same report using a 
-- CASE statement?

SELECT
	CONCAT(c.first_name, " ", c.last_name) AS customer,
        CASE
		WHEN c.points < 2000 THEN "Bronze"
                WHEN c.points BETWEEN 2000 AND 3000 THEN "Silver"
                ELSE "Gold"
	END as type
FROM
	customers c
ORDER BY
	customer;

Although the CASE statement hasn’t yet been covered, I remember learning about it from a different course on T-SQL. I got the same results as the UNION queries.

Is the query using CASE more efficient than performing UNION on three separate queries?

Thank you kindly.