Based on a quick perusal of the DBI source, for the function named 'quote', there's a check for a data type. It won't quote any of the following (at least in my version): 
DBI::SQL_INTEGER
DBI::SQL_SMALLINT
DBI::SQL_DECIMAL
DBI::SQL_FLOAT
DBI::SQL_REAL
DBI::SQL_DOUBLE
DBI::SQL_NUMERIC

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For all other items (for which a type is provided), it looks up the type to see if it needs quoting. If so, it slaps a single quote around it. Any single quotes (or whatever the appropriate literal prefix for that data type) found in the string are doubled.

That's also done if there's no type provided.

I've always found this to be more valuable because it helps avoid some malicious statements -- a user will have more trouble trying to drop one of my tables if his '; DROP TABLE users;' statement is quoted and treated as a literal string.

In reply to Re: Reliability of quoting via DBI placeholders by chromatic
in thread Reliability of quoting via DBI placeholders by princepawn

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