Execute anonymous pl/sql block and get resultset in java

Question

I would like to execute the anonymous PL/SQL and need to get the resultset object. I got the code which can be done by using cursors inside the PL/SQL block.

But the

Answer 1

Here is a self contained example of how to "execute the anonymous PL/SQL and get the resultset object"

import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Types;

import oracle.jdbc.OracleTypes;

public class CallPLSQLBlockWithOneInputStringAndOneOutputStringParameterAndOneOutputCursorParameter {

    public static void main(String[] args) throws Exception {

        DriverManager.registerDriver(new oracle.jdbc.OracleDriver());

        // Warning: this is a simple example program : In a long running application,
        // error handlers MUST clean up connections statements and result sets.

        final Connection c = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:XE", "system", "manager");
        String plsql = "" +
        " declare " +  
        "    p_id varchar2(20) := null; " +
        "    l_rc sys_refcursor;" +
        " begin " +
        "    p_id := ?; " +
        "    ? := 'input parameter was = ' || p_id;" +
        "    open l_rc for " +
        "        select 1 id, 'hello' name from dual " +
        "        union " +
        "        select 2, 'peter' from dual; " +
        "    ? := l_rc;" +
        " end;";

        CallableStatement cs = c.prepareCall(plsql);
        cs.setString(1, "12345");
        cs.registerOutParameter(2, Types.VARCHAR);
        cs.registerOutParameter(3, OracleTypes.CURSOR);

        cs.execute();

        System.out.println("Result = " + cs.getObject(2));

        ResultSet cursorResultSet = (ResultSet) cs.getObject(3);
        while (cursorResultSet.next ())
        {
            System.out.println (cursorResultSet.getInt(1) + " " + cursorResultSet.getString(2));
        } 
        cs.close();
        c.close();
    }
}

The above example query "select 1 id, 'hello' name from dual union select 2, 'peter' from dual;" can be replaced by any query.

Answer 2

Try something like this (pseudo-code):

[create or replace] function get_dataset (p_query in varchar2) return sys_refcursor
as
  l_returnvalue sys_refcursor;
begin
  open l_returnvalue for p_query;
  return l_returnvalue;
end get_dataset;

The REF CURSOR which is returned can be processed like a normal dataset.

And beware of SQL injection when you use an approach like this...

Answer 3

First off, the code you posted is not valid. An anonymous PL/SQL block cannot return an expression. And no PL/SQL block can return the result of a query like that. You would need to do something like declaring a REF CURSOR and opening that cursor using the various SQL statements.

Since an anonymous PL/SQL block cannot return anything to a caller, the architecture you're describing is a problematic. At a minimum, you'd need to modify the anonymous block so that there was a bind variable that your JDBC code could register. Something like (adapted from an example in Menon's Expert Oracle JDBC Programming (note that I may have introduced some minor syntax errors)

CallableStatement stmt := null;
ResultSet         rset := null;
String            query := 'DECLARE 
                              FUNCTION get_result
                                RETURN SYS_REFCURSOR
                              AS
                                l_rc SYS_REFCURSOR;
                              BEGIN
                                OPEN l_rc 
                                 FOR SELECT DISTINCT fundname d, fundname r
                                       FROM some_table
                                      WHERE some_condition
                                      ORDER BY 1;
                                RETURN l_rc;
                              EXCEPTION
                                WHEN others THEN
                                  OPEN l_rc 
                                   FOR SELECT 'Not Available' d, 'Not Available' r
                                         FROM dual;
                                  RETURN l_rc;
                              END get_result;
                            BEGIN
                              ? := get_result;
                            END;';
try {
  cstmt := conn.prepareCall( query );
  cstmt.registerOutParameter( 1, OracleTypes.CURSOR );
  cstmt.execute();
  rset := (ResultSet) cstmt.getObject( 1 );
}
finally {
  <<close cstmt & rset>>
}