问题
How can I get a PL/SQL block to output the results of a SELECT statement the same way as if I had done a plain SELECT?
For example how to do a SELECT like:
SELECT foo, bar FROM foobar;
Hint :
BEGIN
SELECT foo, bar FROM foobar;
END;
doesn\'t work.
回答1:
It depends on what you need the result for.
If you are sure that there's going to be only 1 row, use implicit cursor:
DECLARE
v_foo foobar.foo%TYPE;
v_bar foobar.bar%TYPE;
BEGIN
SELECT foo,bar FROM foobar INTO v_foo, v_bar;
-- Print the foo and bar values
dbms_output.put_line('foo=' || v_foo || ', bar=' || v_bar);
EXCEPTION
WHEN NO_DATA_FOUND THEN
-- No rows selected, insert your exception handler here
WHEN TOO_MANY_ROWS THEN
-- More than 1 row seleced, insert your exception handler here
END;
If you want to select more than 1 row, you can use either an explicit cursor:
DECLARE
CURSOR cur_foobar IS
SELECT foo, bar FROM foobar;
v_foo foobar.foo%TYPE;
v_bar foobar.bar%TYPE;
BEGIN
-- Open the cursor and loop through the records
OPEN cur_foobar;
LOOP
FETCH cur_foobar INTO v_foo, v_bar;
EXIT WHEN cur_foobar%NOTFOUND;
-- Print the foo and bar values
dbms_output.put_line('foo=' || v_foo || ', bar=' || v_bar);
END LOOP;
CLOSE cur_foobar;
END;
or use another type of cursor:
BEGIN
-- Open the cursor and loop through the records
FOR v_rec IN (SELECT foo, bar FROM foobar) LOOP
-- Print the foo and bar values
dbms_output.put_line('foo=' || v_rec.foo || ', bar=' || v_rec.bar);
END LOOP;
END;
回答2:
You can do this in Oracle 12.1 or above:
declare
rc sys_refcursor;
begin
open rc for select * from dual;
dbms_sql.return_result(rc);
end;
I don't have DBVisualizer to test with, but that should probably be your starting point.
For more details, see Implicit Result Sets in the Oracle 12.1 New Features Guide, Oracle Base etc.
For earlier versions, depending on the tool you might be able to use ref cursor bind variables like this example from SQL*Plus:
set autoprint on
var rc refcursor
begin
open :rc for select count(*) from dual;
end;
/
PL/SQL procedure successfully completed.
COUNT(*)
----------
1
1 row selected.
回答3:
From an anonymous block? I'd like to now more about the situation where you think that to be required, because with subquery factoring clauses and inline views it's pretty rare that you need to resort to PL/SQL for anything other than the most complex situations.
If you can use a named procedure then use pipelined functions. Here's an example pulled from the documentation:
CREATE PACKAGE pkg1 AS
TYPE numset_t IS TABLE OF NUMBER;
FUNCTION f1(x NUMBER) RETURN numset_t PIPELINED;
END pkg1;
/
CREATE PACKAGE BODY pkg1 AS
-- FUNCTION f1 returns a collection of elements (1,2,3,... x)
FUNCTION f1(x NUMBER) RETURN numset_t PIPELINED IS
BEGIN
FOR i IN 1..x LOOP
PIPE ROW(i);
END LOOP;
RETURN;
END;
END pkg1;
/
-- pipelined function is used in FROM clause of SELECT statement
SELECT * FROM TABLE(pkg1.f1(5));
回答4:
Create a function in a package and return a SYS_REFCURSOR:
FUNCTION Function1 return SYS_REFCURSOR IS
l_cursor SYS_REFCURSOR;
BEGIN
open l_cursor for SELECT foo,bar FROM foobar;
return l_cursor;
END Function1;
回答5:
The classic “Hello World!” block contains an executable section that calls the DBMS_OUTPUT.PUT_LINE procedure to display text on the screen:
BEGIN
DBMS_OUTPUT.put_line ('Hello World!');
END;
You can checkout it here: http://www.oracle.com/technetwork/issue-archive/2011/11-mar/o21plsql-242570.html
回答6:
if you want see select query output in pl/sql you need to use a explicit cursor. Which will hold active data set and by fetching each row at a time it will show all the record from active data set as long as it fetches record from data set by iterating in loop. This data will not be generated in tabular format this result will be in plain text format. Hope this will be helpful. For any other query you may ask....
set serveroutput on;
declare
cursor c1 is
select foo, bar from foobar;
begin
for i in c1 loop
dbms_output.put_line(i.foo || ' ' || i.bar);
end loop;
end;
回答7:
For versions below 12c, the plain answer is NO, at least not in the manner it is being done is SQL Server.
You can print the results, you can insert the results into tables, you can return the results as cursors from within function/procedure or return a row set from function -
but you cannot execute SELECT statement, without doing something with the results.
SQL Server
begin
select 1+1
select 2+2
select 3+3
end
/* 3 result sets returned */
Oracle
SQL> begin
2 select 1+1 from dual;
3 end;
4 /
select * from dual;
*
ERROR at line 2:
ORA-06550: line 2, column 1:
PLS-00428: an INTO clause is expected in this SELECT statement
回答8:
You need to use Native dynamic SQL. Also, you do not need BEGIN-END to run SQL command:
declare
l_tabname VARCHAR2(100) := 'dual';
l_val1 VARCHAR2(100):= '''foo''';
l_val2 VARCHAR2(100):= '''bar''';
l_sql VARCHAR2(1000);
begin
l_sql:= 'SELECT '||l_val1||','||l_val2||' FROM '||l_tabname;
execute immediate l_sql;
dbms_output.put_line(l_sql);
end;
/
Output:
SELECT 'foo','bar' FROM dual
回答9:
use execute immediate statement
like:
declare
var1 integer;
var2 varchar2(200)
begin
execute immediate 'select emp_id,emp_name from emp'
into var1,var2;
dbms_output.put_line(var1 || var2);
end;
回答10:
Even if the question is old but i will share the solution that answers perfectly the question :
SET SERVEROUTPUT ON;
DECLARE
RC SYS_REFCURSOR;
Result1 varchar2(25);
Result2 varchar2(25);
BEGIN
OPEN RC FOR SELECT foo, bar into Result1, Result2 FROM foobar;
DBMS_SQL.RETURN_RESULT(RC);
END;
回答11:
Cursors are used when your select query returns multiple rows. So, rather using cursor in case when you want aggregates or single rowdata you could use a procedure/function without cursor as well like
Create Procedure sample(id
varchar2(20))as
Select count(*) into x from table
where
Userid=id;
End ;
And then simply call the procedure
Begin
sample(20);
End
This is the actual use of procedure/function mostly wrapping and storing queries that are complex or that requires repeated manipulation with same logic but different data
来源：https://stackoverflow.com/questions/351489/is-it-possible-to-output-a-select-statement-from-a-pl-sql-block