JasperReports: A dynamic table name using a variable? [duplicate] - jasper-reports

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Dynamic parameter of table name in Jasper [duplicate]
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I have this problem with the JasperServer report I'm trying to create:
I have several db tables, named using a name and a date like this:
TABLE_NAME_YYYYMMDD
I want to be able to choose (and do a select from) the table which corresponds to the date submitted by the user from an ordinary Date input control.
I've tried creating a variable (called TABLE_NAME) which uses Java expressions for parsing the date like:
"MY_TABLE_" + new SimpleDateFormat("yyyyMMdd").format($P{RUN_DATE})
and when I print the value of the variable in the report it looks correct. But then I tried using that variable name in the SQL query like:
SELECT column1,column2.. from $V{TABLE_NAME}
but when I tried running the report in Jaspersoft Studio I got this Exception:
net.sf.jasperreports.engine.JRException: net.sf.jasperreports.engine.JRException: Error executing SQL statement for: my_report_x.
at com.jaspersoft.studio.editor.preview.view.control.ReportControler.fillReport(ReportControler.java:511)
at com.jaspersoft.studio.editor.preview.view.control.ReportControler.access$20(ReportControler.java:486)
So it doesn't seem to be working.
I read about the case when the whole table name can be specified in a parameter, and you're supposed to use:
$P!{tableName}
First I tried using that '!' with the variable name like:
..from $V!{TABLE_NAME}
but I got the same Exception.
Then I tried creating a new parameter instead, where "Is For Prompting" is Not checked, and as default value expression I put the same expression as I used in my variable:
"MY_TABLE_" + new SimpleDateFormat("yyyyMMdd").format($P{RUN_DATE})
but I still get the same error when I try to run the report in Jaspersoft Studio.
Does anyone know if there is a way to solve this? -Preferably a way that doesn't take several days to implement since I don't have that time.
I'm using Jaspersoft Studio 6.1.1.final and running the reports in JasperServer 5.5.0.

Answer 1

You should be able to get this to work by wrapping the whole of your FROM expression in the parameter e.g.
<parameter name="pTableName" class="java.lang.String">
<defaultValueExpression><![CDATA["from MY_TABLE_" + new SimpleDateFormat("yyyyMMdd").format($P{RUN_DATE})]]></defaultValueExpression>
</parameter>
And then using this in your SQL as a string literal:
SELECT column1,column2
$P!{pTableName}
WHERE 1 = 1

Answer 2

I just found out what I did wrong.
I admit it was rather stupid, but I only tried running the report in the Preview mode in Jaspersoft Studio. That's when I got the SQL error.
But I assume that the Preview mode does not support dynamic decisions about which table to read from, because when I ignored the Preview errors and published the report to JasperServer, I actually could run it there!
I ended up using the $P!{TABLE_NAME} parameter where the value is what I tried earlier:
"MY_TABLE_" + new SimpleDateFormat("yyyyMMdd").format($P{RUN_DATE})
I can print as much as possible of my SQL here (meaning that I have to replace names since this is a work report) if you want to see it:
select c.column1,c.column2, h.column3 from $P!{TABLE_NAME} h, TABLE2 i, TABLE3 p, TABLE4 ca, TABLE5 c
where h.P_ID = p.P_ID and h.A_ID = ca.A_ID and ca.C_ID = c.C_ID and ca.SOME_VALUE = 1 and ca.OTHER_VALUE = 1
and i.I_ID=h.I_ID
and i.OTHER_ID=1
and h.VALUE_X > 0
order by c.VALUE_Y
So my advice to others who create Jasper reports is not to let yourselves get fooled by the fact that some things don't work in Preview mode. -That might just be the "preview limitations".