MySQL select based on precedence of a column's values - mysql

Question

Say you have a dynamic view of a table that consists of the following entries
| id | type |
| 1 | cat |
| 2 | dog |
| 3 | bunny|
The catch with this is that sometimes there may not be an id with a type of "cat" it could potentially look like
| id | type |
| 1 | dog |
| 2 | bunny|
How would one write a query for this table to select a single row based on precedence of type.
For example, if the ranking of type was cat > dog > bunny, I would want the first entry from that table with the highest ranking condition.
If we call our view pets, which has ORDER BY id ASC then we would have a query that looks something like this
SELECT *
FROM pets
WHERE type = 'cat' > 'dog' > 'bunny' -- here is where I need help
LIMIT 1
I've tried things like
IF EXISTS (SELECT *
FROM pets
WHERE type = "cat")
THEN SELECT * FROM pets WHERE condition = "cat" LIMIT 1
-- etc... down the ranking
Can't seem to get this to work though. Help is much appreciated.

Answer 1

In MySQL, I would use field():
SELECT *
FROM pets
WHERE type IN ('cat', 'dog', 'bunny')
ORDER BY field(type, 'cat', 'dog', 'bunny')
LIMIT 1
If you don't want to deal with the WHERE clause, you can do:
SELECT *
FROM pets
ORDER BY field(type, 'bunny', 'dog', 'cat') DESC
LIMIT 1
You need to go backwards because non-matches are returned as 0.

Answer 2

You can try to use CASE WHEN make the order number in ORDER BY, do your customer order by then LIMIT 1
CREATE TABLE pets(
ID INT,
type VARCHAR(50)
);
INSERT INTO pets VALUES ( 1 , 'cat');
INSERT INTO pets VALUES ( 2 , 'dog');
INSERT INTO pets VALUES ( 3 , 'bunny');
INSERT INTO pets VALUES ( 4 , 'TST');
Query 1:
SELECT *
FROM pets
ORDER BY CASE
WHEN type = 'cat' THEN 1
WHEN type = 'dog' THEN 2
WHEN type = 'bunny' THEN 3
ELSE 4
END
LIMIT 1
Results:
| ID | type |
|----|------|
| 1 | cat |