Cursor Loop_cursorloop-优快云博客

Cursor Loop

Explicitly declared cursor and record

CREATE ORREPLACE PROCEDURE <procedure_name> IS

CURSOR <cursor_name> IS
<SQL statement>

<record_name> <cursor_name>%ROWTYPE;

BEGIN
OPEN <cursor_name>
LOOP
    FETCH <cursor_name> INTO <record_name>;
    EXIT WHEN <cursor_name>%NOTFOUND;

    <other code>
END LOOP;
CLOSE <cursor_name>;
END <procedure_name>;
/

TRUNCATE TABLE loop_test;

DECLARE

CURSOR ao_curIS
SELECT SUBSTR(object_name,1,5) FIRSTFIVE
FROM all_objs
WHERE SUBSTR(object_name,1,5) BETWEEN 'A'AND 'M';

ao_rec ao_cur%ROWTYPE;

BEGIN
OPEN ao_cur;
LOOP
    FETCH ao_curINTO ao_rec;
    EXIT WHEN ao_cur%NOTFOUND;

    INSERT INTO loop_test VALUES (ao_rec.firstfive);
END LOOP;
COMMIT;
CLOSE ao_cur;
END;
/

SELECT COUNT(*) FROM loop_test;

Fetch Demo

-- Demo courtesy of Andy Hassall <andy@andyh.co.uk>

CREATE TABLE t1 (tcol NUMBER);

CREATE TABLE t2 (c NUMBER);

BEGIN
FOR i IN 1..500 LOOP
INSERT INTO t1 VALUES (i);
END LOOP;
END;
/

SELECT COUNT(*) FROM t1;

COMMIT;

CREATE ORREPLACE FUNCTION p (c_in NUMBER)RETURN NUMBER IS

PRAGMA AUTONOMOUS_TRANSACTION;

BEGIN
-- Every time this is called, write a row to table t2
INSERT INTO t2 VALUES (c_in);
COMMIT;
RETURN c_in;
END p;
/

DECLARE
BEGIN
/* Open up a cursor for loop, also selecting
* the "p" function which will write rows to
* t2 for every row fetched from t1. */

FOR crec IN (SELECT tcol, p(tcol)FROM t1) LOOP
-- Break out of the loop immediately
EXIT;
END LOOP;
END;
/

SELECT COUNT(*) FROM t2;

Cursor FOR Loop

Explicitly declared cursor and implicit record declared by the FOR loop

CREATE ORREPLACE PROCEDURE <procedure_name> IS

CURSOR <cursor_name> IS
<SQL statement>

BEGIN
FOR <record_name> IN <cursor_name>
LOOP
<other code>
END LOOP;
END <procedure_name>;
/

TRUNCATE TABLE loop_test;

DECLARE
CURSOR ao_curIS
   SELECT SUBSTR(object_name,1,5) FIRSTFIVE
   FROM all_objs
   WHERE SUBSTR(object_name,1,5) BETWEEN 'N'AND 'W';
BEGIN
FOR ao_recIN ao_cur LOOP
    INSERT INTO loop_test VALUES (ao_rec.firstfive);
END LOOP;
COMMIT;
END;
/

SELECT COUNT(*) FROM loop_test;

A FOR loop with an intrinsic cursor. A record is implicitly declared by the variable in the FOR statement.

BEGIN
FOR <record_name> IN <SQL_statement>
LOOP
<other code>
END LOOP;
END <procedure_name>;
/

TRUNCATE TABLE loop_test;

BEGIN
FOR ao_recIN (
    SELECT SUBSTR(object_name,1,5) FIRSTFIVE
    FROM all_objs
    WHERE SUBSTR(object_name,1,5) BETWEEN 'N'AND 'Z')
LOOP
    INSERT INTO loop_test VALUES (ao_rec.firstfive);
END LOOP;
COMMIT;
END;
/

SELECT COUNT(*) FROM loop_test;

Cursor Loop With
WHERE CURRENT OF Clause

CREATE ORREPLACE PROCEDURE <procedure_name> IS

<cursor definition>

BEGIN
FOR <record_name> IN (<cursor_name>)
LOOP
    <other code>
    UPDATE <table_name>
    SET <column_name> = <value>
    WHERE CURRENT OF <cursor_name>
END LOOP;
END <procedure_name>;
/

CREATE TABLE test (
pid NUMBER(3),
cash NUMBER(10,2));

INSERT INTO test VALUES (100, 10000.73);
INSERT INTO test VALUES (200 25000.26);
INSERT INTO test VALUES (300, 30000.11);
INSERT INTO test VALUES (400, 45000.99);
INSERT INTO test VALUES (500, 50000.08);
COMMIT;

CREATE ORREPLACE PROCEDURE wco IS

CURSOR x_cur IS
SELECT pid, cash
FROM test
WHERE cash < 35000
FOR UPDATE;

BEGIN
FOR x_rec IN x_cur LOOP
    UPDATE test
    SET cash = FLOOR(cash)
    WHERE CURRENT OF x_cur;
END LOOP;
COMMIT;
END wco;
/

exec wco;

SELECT * FROM test;

Nested Cursor Loops

Demo Tables

CREATE TABLE airplanes (
program_id VARCHAR2(3),
line_number NUMBER(10),
customer_id VARCHAR2(4),
order_date DATE,
delivered_date DATE)
PCTFREE 0;

CREATE INDEX programid_idx
ON airplanes (program_id)
PCTFREE 0;

CREATE TABLE parts (
program_id VARCHAR2(3),
line_type VARCHAR2(4),
part_type VARCHAR2(10),
quantity NUMBER(3));

CREATE TABLE ap_parts AS
SELECT a.customer_id, p.part_type, p.quantity
FROM airplanes a, parts p
WHERE a.program_id = p.program_id
AND 1=2;

Load Airplanes

DECLARE
progid airplanes.program_id%TYPE;
lineno airplanes.line_number%TYPE;
custid airplanes.customer_id%TYPE := 'AAL';
orddate airplanes.order_date%TYPE;
deldate airplanes.delivered_date%TYPE;
BEGIN
FOR i IN 1 .. 5 LOOP
    SELECT DECODE(i, 1, '737', 2, '747', 3, '757', 4, '767', 5, '777')
    INTO progid
    FROM DUAL;

    FOR lineno IN 1..250 LOOP
    SELECT DECODE(custid, 'AAL','DAL','DAL','SAL','SAL','ILC',
     'ILC','SWA', 'SWA','NWO','NWO','AAL')
      INTO custid
      FROM DUAL;

    IF progid = '737' THEN
    OrdDate := SYSDATE + lineno;
    DelDate := OrdDate + lineno + 100;
    ELSIF progid = '747' THEN
    OrdDate := SYSDATE + lineno+17;
    DelDate := OrdDate + lineno + 302;
    ELSIF progid = '757' THEN
    OrdDate := SYSDATE + lineno+22;
    DelDate := OrdDate + lineno + 202;
    ELSIF progid = '767' THEN
    OrdDate := SYSDATE + lineno+43;
    DelDate := OrdDate + lineno + 189;
    ELSIF progid = '777' THEN
    OrdDate := SYSDATE + lineno-69;
    DelDate := OrdDate + lineno + 299;
    END IF;

    INSERT INTO airplanes
    (program_id, line_number, customer_id, order_date,
       delivered_date)
    VALUES
      (progid, lineno, custid, orddate, deldate);
END LOOP;
END LOOP;
COMMIT;
END load_airplanes;
/

Load Airplane Parts

BEGIN
INSERT INTO parts VALUES ('737', 'Even', 'Wing', 2);
INSERT INTO parts VALUES ('747', 'Even', 'Wing', 2);
INSERT INTO parts VALUES ('757', 'Even', 'Wing', 2);
INSERT INTO parts VALUES ('767', 'EVen', 'Wing', 2);
INSERT INTO parts VALUES ('777', 'even', 'Wing', 2);
INSERT INTO parts VALUES ('737', 'ODD', 'Wing', 2);
INSERT INTO parts VALUES ('747', 'odd', 'Wing', 2);
INSERT INTO parts VALUES ('757', 'Odd', 'Wing', 2);
INSERT INTO parts VALUES ('767', 'Odd', 'Wing', 2);
INSERT INTO parts VALUES ('777', 'Odd', 'Wing', 2);
INSERT INTO parts VALUES ('737', 'Even', 'Galley', 1);
INSERT INTO parts VALUES ('747', 'EVen', 'Galley', 3);
INSERT INTO parts VALUES ('757', 'EVEN', 'Galley', 3);
INSERT INTO parts VALUES ('767', 'EVeN', 'Galley', 2);
INSERT INTO parts VALUES ('777', 'even', 'Galley', 3);
INSERT INTO parts VALUES ('737', 'ODD', 'Galley', 2);
INSERT INTO parts VALUES ('747', 'odd', 'Galley', 4);
INSERT INTO parts VALUES ('757', 'Odd', 'Galley', 3);
INSERT INTO parts VALUES ('767', 'ODd', 'Galley', 4);
INSERT INTO parts VALUES ('777', 'odD', 'Galley', 4);
INSERT INTO parts VALUES ('737', 'Even', 'Tire', 10);
INSERT INTO parts VALUES ('747', 'Even', 'Tire', 18);
INSERT INTO parts VALUES ('757', 'Even', 'Tire', 12);
INSERT INTO parts VALUES ('767', 'Even', 'Tire', 14);
INSERT INTO parts VALUES ('777', 'EveN', 'Tire', 16);
INSERT INTO parts VALUES ('737', 'ODD', 'Tire', 14);
INSERT INTO parts VALUES ('747', 'Odd', 'Tire', 20);
INSERT INTO parts VALUES ('757', 'Odd', 'Tire', 14);
INSERT INTO parts VALUES ('767', 'Odd', 'Tire', 16);
INSERT INTO parts VALUES ('777', 'Odd', 'Tire', 18);
INSERT INTO parts VALUES ('737', 'Even', 'Seats', 105);
INSERT INTO parts VALUES ('747', 'Even', 'Seats', 255);
INSERT INTO parts VALUES ('757', 'Even', 'Seats', 140);
INSERT INTO parts VALUES ('767', 'Even', 'Seats', 200);
INSERT INTO parts VALUES ('777', 'EveN', 'Seats', 210);
INSERT INTO parts VALUES ('737', 'ODD', 'Seats', 137);
INSERT INTO parts VALUES ('747', 'Odd', 'Seats', 20);
INSERT INTO parts VALUES ('757', 'Odd', 'Seats', 166);
INSERT INTO parts VALUES ('767', 'Odd', 'Seats', 345);
INSERT INTO parts VALUES ('777', 'Odd', 'Seats', 267);
COMMIT;
END;
/

Nested Loops With Static Cursors

CREATE ORREPLACE PROCEDURE nested_loop IS

CURSOR a_curIS
SELECT program_id,line_number, customer_id
FROM airplanes;

a_rec a_cur%ROWTYPE;

CURSOR p_curIS
SELECT part_type, quantity
FROM parts
WHERE program_id = a_rec.program_id
AND UPPER(line_type)=DECODE(MOD(a_rec.line_number,2),0,'EVEN','ODD');

p_rec p_cur%ROWTYPE;

BEGIN
OPEN a_cur;
LOOP
    FETCH a_cur INTO a_rec;
    EXIT WHEN a_cur%NOTFOUND;

    OPEN p_cur;
    LOOP
      FETCH p_cur INTO p_rec;
      EXIT WHEN p_cur%NOTFOUND;
      INSERT INTO ap_parts
      (customer_id, part_type, quantity)
      VALUES
      (a_rec.customer_id, p_rec.part_type, p_rec.quantity);
    END LOOP;
    CLOSE p_cur;

END LOOP;
COMMIT;
CLOSE a_cur;
END nested_loop;
/