WANTED: Query By Example Expression Parser

All Developers,

I develop using MS Visual Studio (non-MFC). Currently, I am looking for ANY work that someone may have already done on:

Requirement:
  a.. Given: A dialog field (accepting keyboard string input which allows any keyboard characters to be entered) on a GUI application dialog.
  b.. Given: Several classes w/ parsing methods specific to dialog field type (INTEGER, DATE, STRING, DECIMAL, etc.)   c.. Needed: Method(s) that allow the operator to basically compose (within these dialog field(s) and without the aid of GUI tools/objects) SQL phrases containing character(s)/string(s) like '(', ')', ',', '<',
'>', '!', '<>' that are to be parsed and converted into SQL phrases and
then stored in a table within an ORACLE database. These user-constructed phrases must be parsed and stored syntactically correct such that these phrases may be used in SQL where clause construction(s) that in effect, basically yield QBE (query-by-example) SQL query objects.
Basically, I'm thinking that somewhere, somebody has gone through the remedial task of building C++ logic that will only allow syntactically correct 'strings' to be constructed (dynamically by the operator would be a major plus)--even if this exact set of QBE characters was not used?  Or similarly, a parsing class/methods for evaluating such user-entered strings?

Thanks in advance for any free leads/ free solutions!! (I'm not shopping for consulting work here, I'm just trying not to re-invent the wheel if possible!)

-Darrin

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