Hi Lance, >>>>> "LJA" == Lance J Andersen wrote: LJA> LJA> The DatabaseMetaData method supportsConvert is used to validate what the LJA> scalar escape function CONVERT can be used for based on the LJA> driver/database combo. LJA> LJA> The javadoc for the supportsConvert(arg1, arg2) should clarified LJA> a bit more. Agreed. LJA> LJA> As far as the name of the SQLTYPE for the Convert scalar function, LJA> drivers were doing this in an inconsistant manner. adding the SQL_ LJA> prefix brings it in line with ODBC. Drivers that do not support the LJA> SQL_ prefix (some drivers support with and without the prefix), will be LJA> required to support the prefix and to continue to optional support LJA> without the prefix. LJA> LJA> Is there an additional question here that i might have missed? Yes, sorry I wasn't clear enough. The question concerns the description in section 15.2.3.1 in the JDBC 4.0 spec, which describes the conversions performed by the ResultSet "getter" methods. These conversions are described in appendix B-2, but the spec also states: "The method DataBaseMetaData.supportsConvert(int fromType, int toType) returns true if the driver supports the given conversion." The point is, this conversion (the "getter conversion") is another (kind of) conversion than that performed by the CONVERT scalar function, and thus the reference to supportsConvert in 15.2.3.1 above is not correct? The signature from "getter" methods is essentially "from: SQLtype to: Java type", whereas the signature for CONVERT is "from: SQLtype, to: SQLtype", right? Perhaps there should have been additional DatabaseMataData methods to allow querying what kind of conversions are supported for "getters" (from SQLtype to Java types) (and vice versa for setters)? Dag LJA> LJA> -lance LJA> LJA> Dag H. Wanvik wrote: LJA> LJA> >Hi, LJA> > LJA> >(Lance, see question to you below) LJA> > LJA> > LJA> > LJA> >>>>>>"DJD" == Daniel John Debrunner wrote: LJA> >>>>>> LJA> >>>>>> LJA> >DJD> LJA> >DJD> Dag H. Wanvik wrote: LJA> >DJD> > DJD> There's some inconsistency here, the ResultSet getter methods are LJA> >DJD> > DJD> converting from SQL data types to Java data types. This supportsConvert LJA> >DJD> > DJD> method takes two arguments, both of which describe SQL data types. LJA> >DJD> > LJA> >DJD> > Yes, you are right. Something for Lance to clarify :) LJA> >DJD> > But it would seem the no-args supportsConvert() should return false LJA> >DJD> > until we add support for CONVERT. LJA> >DJD> LJA> >DJD> And just to be clear, this is the JDBC CONVERT function from section C.5 LJA> >DJD> of JDBC 3.0, correct? LJA> > LJA> >Yes. LJA> > LJA> >DJD> LJA> >DJD> I think there is some issue with CONVERT in JDBC 4.0, where the format LJA> >DJD> of the second argument is changing, from INTEGER to SQL_INTEGER or LJA> >DJD> something like that? LJA> > LJA> >Hmm.. I did a short check.. The DataBaseMetaData.supportsConvert has LJA> >int (from java.sql.Types aka JDBC types/SQLtypes) for both arguments LJA> >(both in JDBC 3.0 and early draft 4.0), which makes sense since the LJA> >API speaks of describing the support/behavior of CONVERT, and this LJA> >conversion all happens in the SQL domain. LJA> > LJA> >[On a side note: actually the Javadoc for supportsConvert speaks of LJA> >(unqualified) CONVERT, without being explicit on this being the C.5 LJA> >escape JDBC CONVERT, not the SQL character set CONVERT, but I guess LJA> >that's kind of obvious..?] LJA> > LJA> >Also, in both the JDBC 3.0 and 4.0 spec, the escape function CONVERT LJA> >has SQLtype as the second argument, "value" being given as the first. LJA> > LJA> >The PreparedStatement "setter"/ ResultSet "getter" functions mappings, LJA> >though, convert from and to Java types, given by the tables in the B LJA> >appendix. LJA> > LJA> >I think the problem is that section 15.2.3.1 in the JDBC 4.0 spec LJA> >(14.2.3.1 in 3.0) erroneously states that LJA> >DataBaseMetaData.supportsConvert says ANYTHING about the mapping for LJA> >getter methods. Interestingly, the corresponding section on conversion LJA> >for *setter* methods makes no mention of LJA> >DataBaseMetaData.supportsConvert (section 13.2.2.1 in 4.0 as well as LJA> >in 3.0). Nor do the IN, OUT, INOUT descriptions. LJA> > LJA> > LJA> > LJA> >>15.2.3.1 Data Type Conversions LJA> >>The recommended ResultSet getter method for each JDBC type is shown LJA> >>in TABLE B-6 on page B-210. This table also shows all of the LJA> >>possible conversions that a JDBC driver may support. The method LJA> >>DataBaseMetaData.supportsConvert(int fromType, int toType) returns LJA> >> LJA> >> LJA> >************************************ LJA> > LJA> > LJA> >>true if the driver supports the given conversion. LJA> >> LJA> >> LJA> > LJA> >Lance, do you agree this is wrong? If it is correct, please explain LJA> >what I am missing here..! LJA> > LJA> >Notwhithstanding this, the Derby implementation of no-args LJA> >DataBaseMetaData.supportsConvert() returns true, indicating we support LJA> >C.5 CONVERT, which we do not AFAICS, and I suggest we make a JIRA for LJA> >that. LJA> > LJA> >Dag LJA> > LJA> > LJA> LJA> LJA> LJA> LJA> LJA> LJA> LJA> The DatabaseMetaData method supportsConvert is used to validate what LJA> the scalar escape function CONVERT can be used for based on the LJA> driver/database combo.
LJA>
LJA> The javadoc for the supportsConvert(arg1, arg2) should clarified a bit LJA> more.
LJA>
LJA> As far as the name of the SQLTYPE for the Convert scalar function, LJA> drivers were doing this in an inconsistant manner.  adding the SQL_ LJA> prefix brings it in line with ODBC.  Drivers that do not support the LJA> SQL_ prefix (some drivers support with and without the prefix), will be LJA> required to support the prefix and to continue to optional support LJA> without the prefix. 
LJA>
LJA> Is there an additional question here that i might have missed?
LJA>
LJA> -lance
LJA>
LJA> Dag H. Wanvik wrote:
LJA>
type="cite"> LJA>
Hi,
LJA> 
LJA> (Lance, see question to you below)
LJA> 
LJA>   
LJA>
LJA>
LJA>
LJA>
LJA>
LJA>
"DJD" == Daniel John Debrunner <djd@debrunners.com> wrote:
LJA>             
LJA>
LJA>
LJA>
LJA>
LJA>
LJA>
DJD> 
LJA> DJD> Dag H. Wanvik wrote:
LJA> DJD> > DJD> There's some inconsistency here, the ResultSet getter methods are
LJA> DJD> > DJD> converting from SQL data types to Java data types. This supportsConvert
LJA> DJD> > DJD> method takes two arguments, both of which describe SQL data types.
LJA> DJD> > 
LJA> DJD> > Yes, you are right. Something for Lance to clarify :) 
LJA> DJD> > But it would seem the no-args supportsConvert() should return false
LJA> DJD> > until we add support for CONVERT.
LJA> DJD> 
LJA> DJD> And just to be clear, this is the JDBC CONVERT function from section C.5
LJA> DJD> of JDBC 3.0, correct?
LJA> 
LJA> Yes. 
LJA> 
LJA> DJD> 
LJA> DJD> I think there is some issue with CONVERT in JDBC 4.0, where the format
LJA> DJD> of the second argument is changing, from INTEGER to SQL_INTEGER or
LJA> DJD> something like that?
LJA> 
LJA> Hmm.. I did a short check..  The DataBaseMetaData.supportsConvert has
LJA> int (from java.sql.Types aka JDBC types/SQLtypes) for both arguments
LJA> (both in JDBC 3.0 and early draft 4.0), which makes sense since the
LJA> API speaks of describing the support/behavior of CONVERT, and this
LJA> conversion all happens in the SQL domain.
LJA> 
LJA> [On a side note: actually the Javadoc for supportsConvert speaks of
LJA> (unqualified) CONVERT, without being explicit on this being the C.5
LJA> escape JDBC CONVERT, not the SQL character set CONVERT, but I guess
LJA> that's kind of obvious..?]
LJA> 
LJA> Also, in both the JDBC 3.0 and 4.0 spec, the escape function CONVERT
LJA> has SQLtype as the second argument, "value" being given as the first.
LJA> 
LJA> The PreparedStatement "setter"/ ResultSet "getter" functions mappings,
LJA> though, convert from and to Java types, given by the tables in the B
LJA> appendix.
LJA> 
LJA> I think the problem is that section 15.2.3.1 in the JDBC 4.0 spec
LJA> (14.2.3.1 in 3.0) erroneously states that
LJA> DataBaseMetaData.supportsConvert says ANYTHING about the mapping for
LJA> getter methods. Interestingly, the corresponding section on conversion
LJA> for *setter* methods makes no mention of
LJA> DataBaseMetaData.supportsConvert (section 13.2.2.1 in 4.0 as well as
LJA> in 3.0). Nor do the IN, OUT, INOUT descriptions.
LJA> 
LJA>   
LJA>
LJA>
15.2.3.1 Data Type Conversions
LJA> The recommended ResultSet getter method for each JDBC type is shown
LJA> in TABLE B-6 on page B-210. This table also shows all of the
LJA> possible conversions that a JDBC driver may support. The method
LJA> DataBaseMetaData.supportsConvert(int fromType, int toType) returns
LJA>     
LJA>
LJA>
************************************ 
LJA>   
LJA>
LJA>
true if the driver supports the given conversion.
LJA>     
LJA>
LJA>

LJA> Lance, do you agree this is wrong? If it is correct, please explain
LJA> what I am missing here..!
LJA> 
LJA> Notwhithstanding this, the Derby implementation of no-args
LJA> DataBaseMetaData.supportsConvert() returns true, indicating we support
LJA> C.5 CONVERT, which we do not AFAICS, and I suggest we make a JIRA for
LJA> that.
LJA> 
LJA> Dag
LJA>   
LJA>
LJA> LJA> LJA> -- Dag H. Wanvik Sun Microsystems, Web Services, Database Technology Group Haakon VII gt. 7b, N-7485 Trondheim, Norway Tel: x43496/+47 73842196, Fax: +47 73842101 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NOTICE: This email message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~