Oracle PL/SQL Tutorial/Cursor/Close Cursor
Содержание
A complete example of using the cursorValue cursor
<source lang="sql">
SQL> SQL> create table product(
2 product_id number(4) not null, 3 product_description varchar2(20) not null 4 );
Table created. SQL> SQL> insert into product values (1,"Java"); 1 row created. SQL> insert into product values (2,"Oracle"); 1 row created. SQL> insert into product values (3,"C#"); 1 row created. SQL> insert into product values (4,"Javascript"); 1 row created. SQL> insert into product values (5,"Python"); 1 row created. SQL> SQL> SQL> create table company(
2 product_id number(4) not null, 3 company_id NUMBER(8) not null, 4 company_short_name varchar2(30) not null, 5 company_long_name varchar2(60) 6 );
Table created. SQL> insert into company values(1,1001,"A Inc.","Long Name A Inc."); 1 row created. SQL> insert into company values(1,1002,"B Inc.","Long Name B Inc."); 1 row created. SQL> insert into company values(1,1003,"C Inc.","Long Name C Inc."); 1 row created. SQL> insert into company values(2,1004,"D Inc.","Long Name D Inc."); 1 row created. SQL> insert into company values(2,1005,"E Inc.","Long Name E Inc."); 1 row created. SQL> insert into company values(2,1006,"F Inc.","Long Name F Inc."); 1 row created. SQL> SQL> SQL> DECLARE
2 CURSOR cursorValue IS 3 SELECT h.product_description,o.rupany_short_name 4 FROM company o,product h 5 WHERE o.product_id =h.product_id 6 ORDER by 2; 7 v_company_rec cursorValue%ROWTYPE; 8 BEGIN 9 OPEN cursorValue; 10 11 LOOP 12 FETCH cursorValue INTO v_company_rec; 13 EXIT WHEN cursorValue%NOTFOUND; 14 dbms_output.put_line(rpad(v_company_rec.product_description,20," ")||" "||rpad(v_company_rec.rupany_short_name,30," ")); 15 END LOOP; 16 CLOSE cursorValue; 17 END; 18 /
Java A Inc. Java B Inc. Java C Inc. Oracle D Inc. Oracle E Inc. Oracle F Inc. PL/SQL procedure successfully completed. SQL> SQL> drop table company; Table dropped. SQL> SQL> drop table product; Table dropped. SQL></source>
Close a cursor
<source lang="sql">
SQL> SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL primary key, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee
2 /
ID FIRST_NAME LAST_NAME 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 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 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> SQL> SQL> CREATE OR REPLACE PROCEDURE employee_count
2 AS 3 v_first_name employee.first_name%TYPE; 4 v_last_name employee.last_name%TYPE; 5 v_row_count PLS_INTEGER := 0; 6 7 CURSOR emp_cur IS 8 SELECT first_name, last_name 9 FROM employee; 10 11 BEGIN 12 13 DBMS_OUTPUT.ENABLE(1000000); 14 15 OPEN emp_cur; 16 LOOP 17 FETCH emp_cur INTO v_first_name, v_last_name; 18 EXIT WHEN emp_cur%NOTFOUND; 19 20 DBMS_OUTPUT.PUT_LINE(v_last_name ||", " ||v_first_name); 21 END LOOP; 22 23 CLOSE emp_cur; 24 25 EXCEPTION 26 WHEN OTHERS 27 THEN 28 DBMS_OUTPUT.PUT_LINE(SQLERRM); 29 END; 30 /
Procedure created. SQL> SQL> SQL> call employee_count(); Martin, Jason Mathews, Alison Smith, James Rice, Celia Black, Robert Green, Linda Larry, David Cat, James Call completed. SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped.</source>
Close cursor after while loop
<source lang="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, "E", "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> SET SERVEROUTPUT ON ESCAPE OFF SQL> SQL> DECLARE
2 v_emp emp%ROWTYPE; 3 4 CURSOR auth_cur IS SELECT * FROM emp; 5 BEGIN 6 OPEN auth_cur; 7 8 FETCH auth_cur INTO v_emp; 9 10 WHILE auth_cur%FOUND LOOP 11 12 DBMS_OUTPUT.PUT_LINE(v_emp.lname); 13 14 FETCH auth_cur INTO v_emp; 15 16 END LOOP; 17 18 CLOSE auth_cur; 19 END; 20 /
B D F H Z PL/SQL procedure successfully completed. SQL> drop table emp; Table dropped.</source>
Close cursor in excpetion handler
<source lang="sql">
SQL> CREATE TABLE EMP(
2 EMPNO NUMBER(4) NOT NULL, 3 ENAME VARCHAR2(10), 4 JOB VARCHAR2(9), 5 MGR NUMBER(4), 6 HIREDATE DATE, 7 SAL NUMBER(7, 2), 8 COMM NUMBER(7, 2), 9 DEPTNO NUMBER(2) 10 );
Table created. SQL> SQL> INSERT INTO EMP VALUES(7369, "SMITH", "CLERK", 7902,TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES(7499, "ALLEN", "SALESMAN", 7698,TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30); 1 row created. SQL> INSERT INTO EMP VALUES(7521, "WARD", "SALESMAN", 7698,TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30); 1 row created. SQL> INSERT INTO EMP VALUES(7566, "JONES", "MANAGER", 7839,TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES(7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30); 1 row created. SQL> INSERT INTO EMP VALUES(7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES(7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES(7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES(7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES(7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30); 1 row created. SQL> INSERT INTO EMP VALUES(7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES(7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES(7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES(7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10); 1 row created.
SQL> create or replace procedure PROCESS_EMP is
2 cursor C is select empno, sal, comm from emp; 3 newSalary number := 10000; 4 begin 5 for i in c loop 6 newSalary := newSalary + i.rum / i.sal; 7 end loop; 8 exception 9 when zero_divide then 10 if C%ISOPEN then 11 close C; 12 end if; 13 end; 14 /
Procedure created. SQL> drop table emp; Table dropped.</source>
Correct Code to Exit a Loop
<source lang="sql">
SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee
2 /
ID FIRST_NAME LAST_NAME 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 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 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> SQL> SQL> SQL> create or replace function f_limit_yn(i_deptNo VARCHAR,i_limit_nr NUMBER, i_income_nr NUMBER)
2 return VARCHAR2 3 is 4 cursor c_emp is 5 select nvl(salary,0) income_nr 6 from employee 7 where id=i_deptNo; 8 9 v_income_nr NUMBER; 10 v_counter_nr NUMBER:=0; 11 v_error_yn VARCHAR2(1):="N"; 12 begin 13 open c_emp; 14 loop 15 fetch c_emp into v_income_nr; 16 exit when c_emp%NOTFOUND; 17 if v_income_nr < i_income_nr then 18 v_counter_nr:=v_counter_nr+1; 19 end if; 20 end loop; 21 close c_emp; 22 return v_error_yn; 23 end; 24 /
Function created. SQL> SQL> select f_limit_yn("01", 1000, 2000) from dual; F_LIMIT_YN("01",1000,2000)
N SQL> SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL></source>
Correctly Written Explicit Cursors
Never add a RETURN clause before closing the cursor.
In the exception-handling block, always check to see whether explicit cursors are open, and if so, close them.
Forgotten cursors that are left open can bring a system to a halt.
<source lang="sql">
SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee(ID, First_Name, Last_Name, 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 Employee
2 /
ID FIRST_NAME LAST_NAME 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 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 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> SQL> SQL> SQL> create or replace function f_getList_tx
2 (i_source_tx VARCHAR2, 3 i_column_tx VARCHAR2, 4 i_filter_tx VARCHAR2, 5 i_separator_tx VARCHAR2) 6 return VARCHAR2 7 is 8 v_string_tx VARCHAR2(4000); 9 v_temp_tx VARCHAR2(4000); 10 v_out_tx VARCHAR2(4000); 11 v_weak_ref sys_refcursor; 12 begin 13 v_string_tx:="select "||i_column_tx|| 14 " from "||i_source_tx|| 15 " where "||i_filter_tx; 16 open v_weak_ref for v_string_tx; 17 loop 18 fetch v_weak_ref into v_temp_tx; 19 exit when v_weak_ref%NOTFOUND; 20 21 if v_out_tx is null then 22 v_out_tx:=v_temp_tx; 23 else 24 v_out_tx:=v_out_tx||i_separator_tx||v_temp_tx; 25 end if; 26 end loop; 27 28 close v_weak_ref; 29 return v_out_tx; 30 exception 31 when others then 32 if v_weak_ref%isOpen then 33 close v_weak_ref; 34 raise; 35 end if; 36 end; 37 /
Function created. SQL> select f_getList_tx("employee","first_name","salary > 200",",") from dual; F_GETLIST_TX("EMPLOYEE","FIRST_NAME","SALARY>200",",")
Jason,Alison,James,Celia,Robert,Linda,David,James SQL> SQL> SQL> SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL></source>