code: def sqlwhere(criteria=None):
      
      if not criteria:
          return ('', [])
      fields = sorted(criteria.keys())
      validate_names(fields)
      values = [criteria[field] for field in fields]
      parts = [field + '=%s' for field in fields]
      sql = ' and '.join(parts)
      return (sql, values)
docs: Generates SQL where clause. Returns (sql, values).
      Criteria is a dictionary of {field: value}.
  
      >>> sqlwhere()
      ('', [])
      >>> sqlwhere({'id': 5})
      ('id=%s', [5])
      >>> sqlwhere({'id': 3, 'name': 'toto'})
      ('id=%s and name=%s', [3, 'toto'])
      >>> sqlwhere({'id': 3, 'name': 'toto', 'createdon': '2013-12-02'})
      ('createdon=%s and id=%s and name=%s', ['2013-12-02', 3, 'toto'])