EXECUTE IMMEDIATE in plsql

Question

How to get a result from this code

EXECUTE IMMEDIATE \'SELECT * FROM \' || table_name

through for loop

The usual m

Answer 1

Here is a simple function which dynamically opens a cursor variable, using the passed table name parameter.

create or replace function get_details_by_dno
    ( p_tab in user_tables.table_name%type
      , p_dno in dept.deptno%type )
    return sys_refcursor
is
    rv sys_refcursor;
    stmt varchar2(32767);
begin
    stmt := 'select * from '
        ||p_tab
        ||' where deptno = :1';
    open rv for stmt using p_dno;
    return rv;
end;
/

It also uses the DEPTNO as a filter; consequently the function will fail if we pass a table which doesn't have such a column.

Some clients can interpret the ref cursor's metadata. For instance JDBC and ODBC ResultSets can do this. SQL*Plus can do it:

SQL> exec :rc := get_details_by_dno('DEPT', 50)

PL/SQL procedure successfully completed.

SQL> print rc

    DEPTNO DNAME          LOC           REGION
---------- -------------- ------------- ----------
        50 HOUSEKEEPING   INTERNAL

SQL> exec :rc := get_details_by_dno('EMP', 50)

PL/SQL procedure successfully completed.

SQL> exec :rc := get_details_by_dno('EMP', 50)

PL/SQL procedure successfully completed.

SQL> print rc

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      8085 TRICHLER   PLUMBER         8061 08-APR-10       3500                    50
      8060 VERREYNNE  PLUMBER         8061 08-APR-08       4000                    50
      8061 FEUERSTEIN PLUMBER         7839 27-FEB-10       4500                    50
      8100 PODER      PLUMBER         8061                 3750                    50

SQL>

PL/SQL cannot do this. So we need to be explicit about the table and column names.

create or replace procedure print_details_by_dno
    ( p_tab in user_tables.table_name%type
      , p_dno in dept.deptno%type )
is
    rc sys_refcursor;
    emp_rec emp%rowtype;
    dept_rec dept%rowtype;
begin
    rc :=  get_details_by_dno( p_tab , p_dno );

    if p_tab = 'EMP' then
        fetch rc into emp_rec;
        while rc%found loop
            dbms_output.put_line('ename='||emp_rec.ename||' empno='||emp_rec.empno);   
            fetch rc into emp_rec;
        end loop;
    elsif p_tab = 'DEPT' then
        fetch rc into dept_rec;
        while rc%found loop
            dbms_output.put_line('dname='||dept_rec.dname);   
            fetch rc into dept_rec;
        end loop;
    end if;
end;
/

Let's see it running:

SQL> set serveroutput on
SQL> exec print_details_by_dno('EMP',50)
ename=TRICHLER empno=8085
ename=VERREYNNE empno=8060
ename=FEUERSTEIN empno=8061
ename=PODER empno=8100

PL/SQL procedure successfully completed.

SQL> exec print_details_by_dno('DEPT',50)
dname=HOUSEKEEPING

PL/SQL procedure successfully completed.

SQL>