[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: XML and LDAP: Common APIs?
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. Yours, John F Schlesinger SysCore Solutions 212 619 5200 x 219 917 886 5895 Mobile -----Original Message----- From: Rob Weltman [mailto:rweltman@n...] Sent: Sunday, August 27, 2000 8:55 PM To: xml-dev@l... 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 - or > maybe I'm barking up the wrong tree? > Suppose you want to search for employees with an employee number higher than 200. You could express that in LDAP filter syntax as "(employeeNumber > 200)". Should the query return a record for the employee with number 1000? It depends on if the value is considered a string or an integer (in LDAP it is determined by the syntax of the attribute). Rob > > Yours, > John F Schlesinger > SysCore Solutions > 212 619 5200 x 219 > 917 886 5895 Mobile > > -----Original Message----- > From: rsanford [mailto:rsanford@n...] > Sent: Friday, August 25, 2000 3:48 PM > To: xml-dev@l... > 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? > > rjsjr > > > -----Original Message----- > > From: John F. Schlesinger [mailto:johns@s...] > > Sent: Friday, August 25, 2000 11:25 AM > > To: 'KenNorth'; xml-dev@l... > > Subject: RE: XML and LDAP: Common APIs? > > > > > > Ken wrote: > > "How do you know whether a query should match a binary '101' or a decimal > > '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 match > > string to some common form, but that's a different problem. In many cases > > 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@e...] > > Sent: Thursday, August 24, 2000 4:37 PM > > To: xml-dev@l... > > Subject: Re: XML and LDAP: Common APIs? > > > > > > > > > > > Francis wrote: > > > "...Xpath (unlike XML-Schema)doesn't understand basic types like dates" > > > > > > 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? > > > > > > > > > > > >
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