比较两个不同表的两个结果集

Question

In the below code I am comparing the two Resultset of the tables S_R_VAL and R_VAL. I need to compare S_NUMBER (from S_R_VAL table) and S_NO (from R_VAL table). While comparing I am getting this error "java.lang.RuntimeException: The two ResultSets contains different number of columns! . Please help in fixing this error.

    String SSQ = "select DISTINCT S_NUMBER from OTG.S_R_VAL" +
                        "  WHERE R_TS = (SELECT MAX(R_TS) FROM OTG.S_R_VAL) order by S_NUMBER";

          String SDS = "SELECT DISTINCT S_NUMBER FROM OTG.S_R_VAL AS STG WHERE S_NUMBER NOT IN" +

                                     "(SELECT S_NO FROM OTG.R_VAL AS REV WHERE STG.S_NUMBER = REV.S_NO )";

          String SSR = "SELECT DISTINCT S_NO FROM OTG.R_VAL where S_NO != 'NULL' order by S_NO";

          String SSO =  "Select O_UID from OTG.OPTY where C_S_NO IN" +

         "( SELECT DISTINCT S_NUMBER FROM OTG.S_R_VAL AS STG WHERE S_NUMBER NOT IN(SELECT S_NO FROM OTG.R_VAL AS REV WHERE STG.S_NUMBER = REV.S_NO ))";

          //Statement statement;

        try {

             connection = DatabaseConnection.getCon();

             statement = connection.createStatement();

             statement1 = connection.createStatement();

          ResultSet SQ = statement.executeQuery(SSQ);

          ResultSet DS = statement.executeQuery(SDS);

          ResultSet SR = statement.executeQuery(SSR);

          ResultSet SO = statement.executeQuery(SSO);


                while (rs.next() && SR.next(){

                    String res1 = rs.getString("S_NUMBER");

                    String res2 = SR.getString("S_NO");

                    StringBuffer updateQuery = new StringBuffer();


                  if (res1.equals(res2)) {
            throw new RuntimeException(String.format("%s and %s aren't equal at common position %d",
                    res1, res2));

                }else 
                {
                     throw new RuntimeException("The two ResultSets contains different number of columns!");
                }
            }

            connection.commit();

Answer 1

You can't reuse the same Statement object because on every new executeQuery() call any ResultSet if already open is closed implicitly.

A ResultSet object is automatically closed when the Statement object that generated it is closed, re-executed, or used to retrieve the next result from a sequence of multiple results.

Check out the JavaDocs for ResultSet .