Meta: Stop using db-fiddle to test for esoteric features/surprising results

[AnyhowStep]

db-fiddle is good for testing widely-used features.

It is terrible for testing esoteric stuff. It is an abstraction for querying multiple types of DBs.

More than once, you've been bitten by using db-fiddle when you have a perfectly running local instance of MySQL...

For example,

SELECT @@/**/sql_mode;

The above is valid on db-fiddle, querying their MySQL DB.

It is definitely invalid on MySQL.

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This suggests db-fiddle does some pre-processing which strips multi-line comments. And, indeed, they do. They completely ignore execution comments/hidden commands.

SELECT 1/*!test*/; -- Equivalent to SELECT 1 AS test

The result on db-fiddle,	1
1

The result on MySQL,	test
1

[AnyhowStep]

There are probably a dozen other similar cases unrelated to multi-line/execution comments that you've forgotten.

[AnyhowStep]

db-fiddle is convenient. This does not make db-fiddle results correct.

[AnyhowStep]

Another good example,

SELECT 1, 1

Db-fiddle result,	1
1

MySQL result,	1	1
1	1

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DB-fiddle seems to merge duplicate columns.

SELECT 1, 2 AS `1`;

Db-fiddle result,	1
2

MySQL result,	1	1
1	2