Why "SELECT ... WHERE id=1=0" returns all rows except one with id=1?

The reason is that the logic should be being evaluated as:

WHERE (id = 1) = 0

This is equivalent to:

WHERE (id = 1) "is false"

Or:

WHERE id <> 1

Try running these examples:

select 1=1=0, 1=2=3, 1=1=0

Default operator precedence works as follows :

WHERE (ID=1)=0

Which resutls false in case of id=1

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