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- From: email@example.com (John F. Schlesinger)
- To: 'Rob Weltman' <firstname.lastname@example.org>, email@example.com
- Date: Mon, 28 Aug 2000 00:20:55 -0400
What we did in EDA/SQL (if I remember right) was to ask the programmer to
specify if the query was using 'string' or 'binary' format.
If I specify 'employeeNumber > 200' using string format, then my 200 is cast
into the datatype of the database. If I am using 'binary' format (which
almost nobody did) then I have to know the datatype (declared in the local
metadata for the database).
The advantage of the string method is that you can ask for an arbitrary
query of the user and send it to the database as a string. The return data
is self describing (as all SQL answer sets are) so that the table can be
formatted for the user.
In any case, I don't think you need to know the datatype to form the query -
though you may need it to understand the response! The SQL functions SUM and
AVERAGE do imply that the fields are in some way numerical.
John F Schlesinger
212 619 5200 x 219
917 886 5895 Mobile
From: Rob Weltman [mailto:firstname.lastname@example.org]
Sent: Sunday, August 27, 2000 8:55 PM
Subject: Re: XML and LDAP: Common APIs?
"John F. Schlesinger" wrote:
> Well, the problem isn't whether the query engine needs to know the data
> type, it is whether I need to know the data type to formulate the query -
> maybe I'm barking up the wrong tree?
Suppose you want to search for employees with an employee number higher
200. You could express that in LDAP filter syntax as "(employeeNumber >
Should the query return a record for the employee with number 1000? It
on if the value is considered a string or an integer (in LDAP it is
by the syntax of the attribute).
> John F Schlesinger
> SysCore Solutions
> 212 619 5200 x 219
> 917 886 5895 Mobile
> -----Original Message-----
> From: rsanford [mailto:email@example.com]
> Sent: Friday, August 25, 2000 3:48 PM
> To: firstname.lastname@example.org
> Subject: RE: XML and LDAP: Common APIs?
> for single values the query engine wouldn't need to
> know what the data type was but what about range
> queries. for example, how would you search for
> records where a date is between 2 march 98 and 4
> august 99?
> > -----Original Message-----
> > From: John F. Schlesinger [mailto:email@example.com]
> > Sent: Friday, August 25, 2000 11:25 AM
> > To: 'KenNorth'; firstname.lastname@example.org
> > Subject: RE: XML and LDAP: Common APIs?
> > Ken wrote:
> > "How do you know whether a query should match a binary '101' or a
> > '101' if you don't use data types?"
> > I don't think I need to know that to formulate a query. The
> > system that does
> > the matching will have to cast both the things being matched and my
> > string to some common form, but that's a different problem. In many
> > everything is cast to a string - then my "101" matches ether a
> > decimal "101"
> > or a binary "101". If I meant a decimal "101" and it matched to a binary
> > "101" by mistake, then I was querying the wrong field.
> > Yours,
> > John F Schlesinger
> > SysCore Solutions
> > 212 619 5200 x 219
> > 917 886 5895 Mobile
> > -----Original Message-----
> > From: KenNorth [mailto:KenNorth@email.msn.com]
> > Sent: Thursday, August 24, 2000 4:37 PM
> > To: email@example.com
> > Subject: Re: XML and LDAP: Common APIs?
> > > Francis wrote:
> > > "...Xpath (unlike XML-Schema)doesn't understand basic types like
> > >
> > > I don't need data types to query.
> > Okay, let's say you have a value of '101'.
> > How do you know whether a query should match a binary '101' or a decimal
> > '101' if you don't use data types?