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DML RETURNING INTO Clause

2012-05-12 23:05 274 查看
The
RETURNING INTO
clause allows us to return column values for rows affected by DML statements. The following test table is used to demonstrate this clause.

DROP TABLE t1;
DROP SEQUENCE t1_seq;

CREATE TABLE t1 (
  id NUMBER(10),
  description VARCHAR2(50),
  CONSTRAINT t1_pk PRIMARY KEY (id)
);

CREATE SEQUENCE t1_seq;

INSERT INTO t1 VALUES (t1_seq.nextval, 'ONE');
INSERT INTO t1 VALUES (t1_seq.nextval, 'TWO');
INSERT INTO t1 VALUES (t1_seq.nextval, 'THREE');
COMMIT;


When we insert data using a sequence to generate our primary key value, we can return the primary key value as follows.

SET SERVEROUTPUT ON
DECLARE
  l_id t1.id%TYPE;
BEGIN
  INSERT INTO t1 VALUES (t1_seq.nextval, 'FOUR')
  RETURNING id INTO l_id;
  COMMIT;

  DBMS_OUTPUT.put_line('ID=' || l_id);
END;
/
ID=4

PL/SQL procedure successfully completed.

SQL>


The syntax is also available for update and delete statements.

SET SERVEROUTPUT ON
DECLARE
  l_id t1.id%TYPE;
BEGIN
  UPDATE t1
  SET    description = description
  WHERE  description = 'FOUR'
  RETURNING id INTO l_id;

  DBMS_OUTPUT.put_line('UPDATE ID=' || l_id);

  DELETE FROM t1
  WHERE  description = 'FOUR'
  RETURNING id INTO l_id;

  DBMS_OUTPUT.put_line('DELETE ID=' || l_id);

  COMMIT;
END;
/
UPDATE ID=4
DELETE ID=4

PL/SQL procedure successfully completed.

SQL>


When DML affects multiple rows we can still use the
RETURNING INTO
, but now we must return the values into a collection using the
BULK COLLECT
clause.

SET SERVEROUTPUT ON
DECLARE
  TYPE t_tab IS TABLE OF t1.id%TYPE;
  l_tab t_tab;
BEGIN
  UPDATE t1
  SET    description = description
  RETURNING id BULK COLLECT INTO l_tab;

  FOR i IN l_tab.first .. l_tab.last LOOP
    DBMS_OUTPUT.put_line('UPDATE ID=' || l_tab(i));
  END LOOP;

  COMMIT;
END;
/
UPDATE ID=1
UPDATE ID=2
UPDATE ID=3

PL/SQL procedure successfully completed.

SQL>


We can also use the
RETURNING INTO
clause in combination with bulk binds.

SET SERVEROUTPUT ON
DECLARE
  TYPE t_desc_tab IS TABLE OF t1.description%TYPE;
  TYPE t_tab IS TABLE OF t1%ROWTYPE;
  l_desc_tab t_desc_tab := t_desc_tab('FIVE', 'SIX', 'SEVEN');
  l_tab   t_tab;
BEGIN
  
  FORALL i IN l_desc_tab.first .. l_desc_tab.last
    INSERT INTO t1 VALUES (t1_seq.nextval, l_desc_tab(i))
    RETURNING id, description BULK COLLECT INTO l_tab;

  FOR i IN l_tab.first .. l_tab.last LOOP
    DBMS_OUTPUT.put_line('INSERT ID=' || l_tab(i).id || 
                         ' DESC=' || l_tab(i).description);
  END LOOP;

  COMMIT;
END;
/
INSERT ID=5 DESC=FIVE
INSERT ID=6 DESC=SIX
INSERT ID=7 DESC=SEVEN

PL/SQL procedure successfully completed.

SQL>


This functionality is also available from dymanic SQL.

SET SERVEROUTPUT ON
DECLARE
  TYPE t_tab IS TABLE OF t1.id%TYPE;
  l_tab t_tab;
BEGIN
  EXECUTE IMMEDIATE 'UPDATE t1
                     SET    description = description
                     RETURNING id INTO :l_tab'
  RETURNING BULK COLLECT INTO l_tab;

  FOR i IN l_tab.first .. l_tab.last LOOP
    DBMS_OUTPUT.put_line('UPDATE ID=' || l_tab(i));
  END LOOP;

  COMMIT;
END;
/
UPDATE ID=1
UPDATE ID=2
UPDATE ID=3

PL/SQL procedure successfully completed.

SQL>
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