You could build a hash of regexes, something like this (the regexes are just given as quick simplistic examples, I haven't thought very carefully about them).

my %validate = (
     INT => qr /^[+-]?\d+$/,
     DEC => qr /^[+-]?\d*\.?\d*$/,
     #etc.
);
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and then use it to validate your individual fields.

You might actually take it one step further and build a dispatch table, something like this:

my %actions = (
     INT => sub { return 1 if $_[0] =~ /^[+-]?\d+$/},
     DEC => sub { return 1 if $_[0] =~ /^[+-]?\d*\.?\d*$/},
     VARCHAR(5)=> \&validate_varchar_5(@_),
     #etc.
);
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This is a very rough untested example, I just want to convey the general idea.

You don't say enough about what you have done to figure out whether these techniques will be beneficial.