[ http://issues.apache.org/jira/browse/DERBY-1483?page=comments#action_12419722 ]
Stan Bradbury commented on DERBY-1483: -------------------------------------- Thanks Dan - I find type resolution like this unpredictable (being relatively inexperienced with Java outside of JDBC). Is there a reference I can use to look-up how a Derby datatype will be resolved in cases like this? I would find it helpful to have this available in the manuals by either including a table or a reference to the Java/JDBC spec. Or would a better method to include the full method signature in the 'EXTERNAL NAME" clause? I've seen no examples of anything other than the class and method name and it did not occur to me that including the parameter type was allowed. Addressing this in the documents would also help non-Java expert-types to use this functionality. I would like to spin-off an appropriate document enhancement for this to help others in using this functionality. > Java Function defined with a BIGINT parameter invokes the method with a > signature of method(long) rather than method(Long) > -------------------------------------------------------------------------------------------------------------------------- > > Key: DERBY-1483 > URL: http://issues.apache.org/jira/browse/DERBY-1483 > Project: Derby > Type: Bug > Versions: 10.1.2.1 > Reporter: Stan Bradbury > Priority: Minor > > Calling a function passing BIGINT to a method accepting Long fails with the > message: > ERROR 42X50: No method was found that matched the method call > derbyJavaUtils.bigintToHexString(long), tried all combinations of object and > primitive types and any possible type conversion for any parameters the > method call may have. The method might exist but it is not public and/or > static, or the parameter types are not method invocation convertible. > The method needs to accept the primative type: long to work. BIGINT as > docuemented as having a compile time type of java.lang.Long - this is why I > expected the example method to work: see the Reference manual: > http://db.apache.org/derby/docs/10.1/ref/rrefsqlj30435.html. > > Example: define the function bigintToHexString to accept a BIGINT parameter > (see below) and reference the corresponding java method bigintToHexString > (shown below) that accepts a Long. Add the jarfile with the class to the DB, > setup the database classpath and invoke with the query shown. > >>> Java Class: > import java.sql.*; > public class derbyJavaUtils > { > // bigintToHexString > public static String bigintToHexString(Long myBigint) > { > return myBigint.toHexString(myBigint.longValue()); > } > // bigintToHexString2 - this will work if used for the function > public static String bigintToHexString2(long myBigint) > { > Long myLong = null; > return myLong.toHexString(myBigint); > } > } > >> COMPILE IT AND JAR IT : jar -cvf derbyJavaUtils.jar DerbyJavaUtils.class > >> Setup the function as follows in a database: > .. CALL sqlj.install_jar( 'derbyJavaUtils.jar','APP.derbyJavaUtils',0); > .. CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY('derby.database.classpath', > 'APP.derbyJavaUtils'); > .. CREATE FUNCTION app.bigintToHexString(hexString bigint) > RETURNS VARCHAR(16) > PARAMETER STYLE JAVA NO SQL > LANGUAGE JAVA > EXTERNAL NAME 'derbyJavaUtils.bigintToHexString' > === One possible test query: > select 'C' || bigintToHexString2(CONGLOMERATENUMBER) || '.dat', TABLENAME, > ISINDEX > from SYS.SYSCONGLOMERATES a, SYS.SYSTABLES b > where a.TABLEID = b.TABLEID > As mention in the code comments the method: bigintToHexString2 - will work > if used for the function -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
