Hi John,
MySQL simply doesn't support it, only DISTINCT (without on) is
supported:
http://dev.mysql.com/doc/refman/4.1/en/select.html
Best regards,
Geert
On 25 Sep 2006, at 01:02, John Lukar wrote:
Hi folks,
is it true that distinctOn is not supported by MySql JDBC driver ? I
have tried both versions:
mysql-connector-java-5.0.3
mysql-connector-java-3.1.13
on MySql versions:
4.1.10a-nt
5.0.22-Debian_0ubuntu6.06.2-log
and all the same results.
below is the SQL:
Select select = new Select(getDatasource())
.distinctOn("question.id QuestionID, question.qText
Question, answer.id AnswerID, answer.text Answer,
question_answer.correct_answer CorrectA")
.from("question_answer")
.from("answer")
.from("question")
.where( "answer.id = answer_id")
.whereAnd("question_id = 3")
.whereAnd("question.id = question_id");
System.out.println(" Query: "+select.getSql());
// fetch every row in the resultset and forward the processing
// of the data to the DisplayProcessor
executeFetchAll(select, processor);
Below is the stack trace:
om.uwyn.rife.database.exceptions.UnsupportedSqlFeatureException: The
'DISTINCT ON' feature isn't supported by the driver
'com.mysql.jdbc.Driver'.
at com.uwyn.rife.database.queries.Select.getSql(Select.java:291)
at com.uwyn.ecalendar.ExamQuestionManager.display
(ExamQuestionManager.java:56)
at com.uwyn.ecalendar.elements.DisplayExamQuestions.processElement
(DisplayExamQuestions.java:56)
at com.uwyn.rife.engine.ElementContext.processContext
(ElementContext.java:443)
at com.uwyn.rife.engine.RequestState.service(RequestState.java:342)
at com.uwyn.rife.engine.Gate.handleRequest(Gate.java:421)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke
(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke
(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.uwyn.rife.servlet.RifeFilter.doFilter(RifeFilter.java:142)
at org.mortbay.jetty.servlet.WebApplicationHandler
$CachedChain.doFilter(WebApplicationHandler.java:823)
at org.mortbay.jetty.servlet.WebApplicationHandler.dispatch
(WebApplicationHandler.java:473)
at org.mortbay.jetty.servlet.ServletHandler.handle
(ServletHandler.java:567)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1565)
at org.mortbay.jetty.servlet.WebApplicationContext.handle
(WebApplicationContext.java:635)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1517)
at org.mortbay.http.HttpServer.service(HttpServer.java:954)
at org.mortbay.http.HttpConnection.service(HttpConnection.java:814)
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--
Geert Bevin
Uwyn "Use what you need" - http://uwyn.com
RIFE Java application framework - http://rifers.org
Music and words - http://gbevin.com
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