SOUNDEX function should not be case-sensitive

[ullenboom]

Currently

select soundex('TOM'), soundex('tom')

is leading to T500 and t500.

The result should be uppper case, as you are referring to MS-SQL in the code anyway: https://learn.microsoft.com/en-us/sql/t-sql/functions/soundex-transact-sql?view=sql-server-ver16

[katzyn]

This function is not expected to be compatible with other database systems, because they already have different implementations. I don't see any references to MS SQL in documentation or implementation of SOUNDEX (but implementation of DIFFERENCE mentions it together with HSQLDB).

Anyway, encoding of SOUNDEX shouldn't preserve the case of the first English letter, it's a zero day bug, but nobody cared before, possibly because this function is too specialized and is expected to be used only with English names and first letter of names is always capitalized.