Oracle PL/SQL Tutorial/Cursor/ref cursor
Содержание
Create and use reference cursor
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SQL> SQL> create table big_table as select * from all_objects; Table created. SQL> SQL> declare
2 c sys_refcursor; 3 type array is table of big_table%rowtype index by binary_integer; 4 l_rec array; 5 begin 6 for i in 1 .. 5 7 loop 8 open c for select * from big_table ORDER BY OWNER; 9 fetch c bulk collect into l_rec limit i*1000; 10 close c; 11 end loop; 12 end; 13 /
PL/SQL procedure successfully completed. SQL> SQL> drop table big_table; Table dropped. SQL></source>
Creating a REF CURSOR datatype
The REF CURSOR datatype cannot be used outside a PL/SQL environment.
There are two kinds of REF CURSOR types: weak and strong.
A weak REF CURSOR can point to any data set, as shown here:
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declare
type weak_rcty is ref cursor; c_weak rcty weak_rcty;</source>
REF CURSOR custom type
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SQL> CREATE TABLE book (
2 isbn CHAR(10) PRIMARY KEY, 3 category VARCHAR2(20), 4 title VARCHAR2(100), 5 num_pages NUMBER, 6 price NUMBER, 7 copyright NUMBER(4), 8 emp1 NUMBER, 9 emp2 NUMBER, 10 emp3 NUMBER 11 );
Table created. SQL> SQL> INSERT INTO book (isbn, category, title, num_pages, price, copyright, emp1, emp2, emp3)
2 VALUES ("1", "Database", "Oracle", 563, 39.99, 2009, 1, 2, 3);
1 row created. SQL> INSERT INTO book (isbn, category, title, num_pages, price, copyright, emp1, emp2)
2 VALUES ("2", "Database", "MySQL", 765, 44.99, 2009, 4, 5);
1 row created. SQL> INSERT INTO book (isbn, category, title, num_pages, price, copyright, emp1, emp2, emp3)
2 VALUES ("3", "Database", "SQL Server", 404, 39.99, 2001, 6, 7, 8);
1 row created. SQL> SQL> SQL> SET SERVEROUTPUT ON ESCAPE OFF SQL> SQL> DECLARE
2 3 TYPE book_typ IS REF CURSOR RETURN book%ROWTYPE; 4 cv_book book_typ; 5 v_book book%ROWTYPE; 6 7 BEGIN 8 9 DBMS_OUTPUT.ENABLE(1000000); 10 11 OPEN cv_book FOR SELECT * FROM book WHERE isbn = "1"; 12 13 FETCH cv_book INTO v_book; 14 15 DBMS_OUTPUT.PUT_LINE(v_book.title||" is "||v_book.price); 16 17 CLOSE cv_book; 18 END; 19 /
Oracle is 39.99 PL/SQL procedure successfully completed. SQL> SQL> drop table book; Table dropped.</source>
Reference cursor
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SQL> SQL> CREATE TABLE emp (
2 id NUMBER PRIMARY KEY, 3 fname VARCHAR2(50), 4 lname VARCHAR2(50) 5 );
Table created. SQL> SQL> INSERT INTO emp (id, fname, lname)VALUES (1, "A", "B"); 1 row created. SQL> INSERT INTO emp (id, fname, lname)VALUES (2, "C", "D"); 1 row created. SQL> INSERT INTO emp (id, fname, lname)VALUES (3, "Enn", "F"); 1 row created. SQL> INSERT INTO emp (id, fname, lname)VALUES (4, "G", "H"); 1 row created. SQL> INSERT INTO emp (id, fname, lname)VALUES (5, "G", "Z"); 1 row created. SQL> SQL> SQL> SET SERVEROUTPUT ON ESCAPE OFF SQL> SQL> CREATE OR REPLACE PROCEDURE emp_sel (cv_results IN OUT SYS_REFCURSOR)
2 IS 3 BEGIN 4 OPEN cv_results FOR SELECT id, fname, lname FROM emp; 5 END; 6 /
Procedure created. SQL> SQL> VARIABLE x REFCURSOR SQL> SQL> EXEC emp_sel(:x) PL/SQL procedure successfully completed. SQL> SQL> print x
ID FNAME
--------------------------------------------------
LNAME
1 A
B
2 C
D
3 Enn
F
4 G
H
5 G
Z
5 rows selected. SQL> SQL> drop table emp; Table dropped. SQL></source>
Reference value in a cursor by cursor variable
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SQL> SQL> -- create demo table SQL> create table emp(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 fname VARCHAR2(10 BYTE), 4 lname VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into emp(ID, fname, lname, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer") 3 /
1 row created. SQL> insert into emp(ID, fname, lname, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester") 3 /
1 row created. SQL> insert into emp(ID, fname, lname, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester") 3 /
1 row created. SQL> insert into emp(ID, fname, lname, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager") 3 /
1 row created. SQL> insert into emp(ID, fname, lname, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester") 3 /
1 row created. SQL> insert into emp(ID, fname, lname, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester") 3 /
1 row created. SQL> insert into emp(ID, fname, lname, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager") 3 /
1 row created. SQL> insert into emp(ID, fname, lname, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester") 3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from emp
2 /
ID FNAME LNAME START_DAT END_DATE SALARY CITY
---------- ---------- --------- --------- ---------- ----------
DESCRIPTION
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester
ID FNAME LNAME START_DAT END_DATE SALARY CITY
---------- ---------- --------- --------- ---------- ----------
DESCRIPTION
04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester
ID FNAME LNAME START_DAT END_DATE SALARY CITY
---------- ---------- --------- --------- ---------- ----------
DESCRIPTION
07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester
8 rows selected.
SQL> CREATE OR REPLACE PROCEDURE myProcedure
2 AS 3 CURSOR myCursor IS SELECT id, fname FROM emp; 4 TYPE firstNameType IS TABLE OF emp.fname%type INDEX BY emp.id%type; 5 ch firstNameType; 6 i integer := 0; 7 imax integer; 8 BEGIN 9 FOR j IN myCursor LOOP 10 i := i + 1; 11 ch(i) := j.fname; 12 END LOOP; 13 dbms_output.put_line(ch("James")); 14 END myProcedure; 15 /
Procedure created. SQL> SQL> exec myProcedure; SQL> SQL> SQL> SQL> -- clean the table SQL> drop table emp
2 /
Table dropped. SQL> SQL> SQL></source>
Timing a ref cursor
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SQL> SQL> declare
2 type rc is ref cursor; 3 l_rc rc; 4 l_dummy all_objects.object_name%type; 5 l_start number default dbms_utility.get_time; 6 begin 7 for i in 1 .. 1000 8 loop 9 open l_rc for 10 "select object_name 11 from all_objects 12 where object_id = :x" 13 using i; 14 fetch l_rc into l_dummy; 15 close l_rc; 16 end loop; 17 dbms_output.put_line 18 ( round( (dbms_utility.get_time-l_start)/100, 2 ) || 19 " seconds..." ); 20 end; 21 /
.63 seconds... PL/SQL procedure successfully completed. Elapsed: 00:00:00.70 SQL> SQL> set timing off</source>