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From "Chris Murphy (www.strandz.org)" <ch...@strandz.org>
Subject SQLTemplate query with MIN() group function
Date Sat, 20 Aug 2011 15:07:32 GMT
I am trying to do this query through Cayenne:

select MIN( RD.sampleTime)
from SamplePoint SP, GasPoint GP, Reading RD
where RD.gasPoint_fk = GP.pk
and GP.samplePoint_fk = SP.pk
and SP.name = "54_CT_gas";

This is the code I am using:

String query =
    //"select #result('MIN( RD.sampleTime)' 'java.util.Date')\n" +
    "select MIN( RD.sampleTime)\n" +
    "from samplePoint SP, gasPoint GP, Reading RD\n" +
    "where RD.gasPoint_fk = GP.pk\n" +
    "and GP.samplePoint_fk = SP.pk\n" +
    "and SP.name = $nameParam";
SQLTemplate rawSelect = new SQLTemplate( SamplePoint.class, query);
rawSelect.setParameters( Collections.singletonMap( "nameParam",
"\"54_CT_gas\""));
DataContext context = (DataContext)dataStore.getEM().getActualEM();
List result = context.performQuery( rawSelect);
if(result.size() == 1)
{
    Object resultObj = result.get( 0);
    Err.pr( "result: " + resultObj);
    if(resultObj == null)
    {
        Err.pr( "One row returned but contains a null object");
    }
    else
    {
        Err.pr( "Result is of type " + resultObj.getClass().getName());
    }
}

The query works without any error, but this is what is output:

result: null
One row returned but contains a null object

Can anyone point me in the right direction as to what I might be doing
wrong?

thanks ~ Chris Murphy

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