Java的SQL Server查询没有结果

Question

• OS: Windows Server 2012
• Database: SQL Server 2012
• Additional Software: jdk-7u51-windows-x64, apache-tomcat-7.0.50, Ant 1.9.3

I'm migrating a website from Linux/MySQL to Windows/SQL Server. One of the problems I have: I'd like to execute the SQL query

SELECT 
    r.PatientID, r.StudyDate, r.StudyTime, MeanCTDIvol_in_mGy, 
    @@ROWCOUNT as 'rowcount' 
FROM 
    report r 
INNER JOIN 
    ct_irradiation_events e ON r.rdsr_id = e.rdsr_id  
INNER JOIN 
    patient_age_categories a ON (DATEDIFF(day, r.PatientsBirthDate, r.StartOfXrayIrradiation) <= a.max_age_days AND DATEDIFF(day, r.PatientsBirthDate, r.StartOfXrayIrradiation) >= a.min_age_days AND a.description = 'Erwachsene')  WHERE MeanCTDIvol_in_mGy IS NOT NULL AND r.DeviceObserverUID = '2.25.80710267121025297646217319020776291293' AND ProcedureCodeShort = 'CTBTHABDA'AND e.CTAcquisitionType != 'Constant Angle Acquisition' AND DATEDIFF(day, '2013-11-20', r.StudyDate) >=0 AND DATEDIFF(day, '2014-02-20', r.StudyDate) <=0;

When I execute it in SQL Server Management Studio, I receive the result. When executing the same in java via JDBC I do not receive a result.

How I like to do it (only a snippet of the code):

conn = EstablishDBConnection();
PreparedStatement pst = null;
ResultSet rs = null;

try {
          String sQuery = "SELECT r.PatientID, r.StudyDate, r.StudyTime, " + measure + ", @@ROWCOUNT as 'rowcount'  FROM report r  INNER JOIN ct_irradiation_events e ON r.rdsr_id=e.rdsr_id  INNER JOIN patient_age_categories a ON (DATEDIFF(day, r.PatientsBirthDate, r.StartOfXrayIrradiation) <= a.max_age_days AND DATEDIFF(day, r.PatientsBirthDate, r.StartOfXrayIrradiation) >= a.min_age_days AND a.description = ?)  WHERE " + measure + " IS NOT NULL AND r.DeviceObserverUID = ? AND ProcedureCodeShort = ? AND e.CTAcquisitionType != 'Constant Angle Acquisition' AND DATEDIFF(day, ?, r.StudyDate) >=0 AND DATEDIFF(day, ?, r.StudyDate) <=0;";
pst = conn.prepareStatement(sQuery);
pst.setString(1, agedescription);
pst.setString(2, devicecode);
pst.setString(3, proccode);
pst.setString(4, date_from);
pst.setString(5, date_until);
rs = pst.executeQuery();
noOfValues = rs.getInt("rowcount");
servlet_context.log("noOfValues: " + noOfValues);
DBValues = new double[noOfValues];

while (rs.next()) {
  JSONArray jRow = new JSONArray();
  jRow.put(rs.getDate("StudyDate").toString() + " " + rs.getTime("StudyTime").toString());
  jRow.put(rs.getDouble(measure));
  jRow.put(rs.getString("PatientID"));
  jData.put(jRow);
  DBValues[i] = rs.getDouble(measure);
  i++;
}

I've also tried:

conn = EstablishDBConnection();
PreparedStatement pst = null;
ResultSet rs = null;

try {
                pst = conn.prepareStatement("SELECT r.PatientID, r.StudyDate, r.StudyTime, MeanCTDIvol_in_mGy, @@ROWCOUNT as 'rowcount' FROM report r INNER JOIN ct_irradiation_events e ON r.rdsr_id=e.rdsr_id  INNER JOIN patient_age_categories a ON (DATEDIFF(day, r.PatientsBirthDate, r.StartOfXrayIrradiation) <= a.max_age_days AND DATEDIFF(day, r.PatientsBirthDate, r.StartOfXrayIrradiation) >= a.min_age_days AND a.description = 'Erwachsene')  WHERE MeanCTDIvol_in_mGy IS NOT NULL AND r.DeviceObserverUID = '2.25.80710267121025297646217319020776291293' AND ProcedureCodeShort = 'CTBTHABDA'AND e.CTAcquisitionType != 'Constant Angle Acquisition' AND DATEDIFF(day, '2013-11-20', r.StudyDate) >=0 AND DATEDIFF(day, '2014-02-20', r.StudyDate) <=0;");
                rs = pst.executeQuery();

The variable "measure" is defined further up in the code. However, both versions do not give me a result and finnaly I get java.lang.NullPointerException when trying to read the the empty result.

Other queries work just fine, so the connection to the data base works (at least partly). I don't have any other error in the logs expect from:

Feb 20, 2014 3:49:48 PM org.apache.catalina.core.ApplicationContext log
INFO: The result set has no current row.
Feb 20, 2014 3:49:48 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [RDSRServlet] in context with path [/RDSRServlet] threw exception
java.lang.NullPointerException
    at ch.ksa.rdsr.web.DatabaseJSON.getCtTimeline(Unknown Source)

Thank you for any help!

Edit

Query that works:

String sQuery = "SELECT id, DeviceObserverName, DeviceObserverUID FROM devices WHERE Modality = ? ORDER BY DeviceObserverName ASC, id ASC;";
            pst = conn.prepareStatement(sQuery);
            pst.setString(1, modcode);
            rs = pst.executeQuery();

measure is MeanCTDIvol_in_mGy as can be seen in the second try i made.

Answer 1

The problem was that

noOfValues = rs.getInt("rowcount");

came before

rs.next()

I have to change to code then it'll work. I'll store the results in an ArrayList so I don't have to know the number of results at the beginning. Thanks anyway.