Support Format Modifiers for String Conversion

A lack of support for "format modifiers" or "template patterns" while converting numeric and potentially other types to strings is a hinderance on usability.

There may not be a way to do this as part of the SQL Standard, most database have a common extension to type conversion functions such as CONVERT() CAST() or TO_CHAR() that take a "printf" style format string as an argument. Locale awareness may have to be taken into consideration.

For example Postgresql uses this syntax to add a thousand separator:

to_char(148.5, '999D999')