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== A complete example of using SELECT FOR UPDATE cursors==



<source lang="sql">
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 sec_product(
2 product_id number(4) not null,
3 product_description varchar2(20) not null
4 );
Table created.
SQL>
SQL>
SQL> BEGIN
2 INSERT INTO sec_product
3 SELECT * FROM product;
4 COMMIT;
5 END;
6 /
PL/SQL procedure successfully completed.
SQL> DECLARE
2 CURSOR myCursor IS
3 SELECT * FROM sec_product FOR UPDATE OF product_description;
4 v_product_description VARCHAR2(20);
5 BEGIN
6 FOR idx IN myCursor LOOP
7 v_product_description :=UPPER(idx.product_description);
8 UPDATE sec_product
9 SET product_description =v_product_description
10 WHERE CURRENT OF myCursor;
11 END LOOP;
12 COMMIT;
13 END;
14 /
PL/SQL procedure successfully completed.
SQL>
SQL> drop table product;
Table dropped.
SQL> drop table sec_product;
Table dropped.</source>

== Check error code and Raise the proper error==



<source lang="sql">
SQL>
SQL>
SQL> CREATE OR REPLACE PROCEDURE myraise (err_in IN INTEGER := SQLCODE,msg_in IN VARCHAR2 := SQLERRM)
2 IS
3 BEGIN
4 IF err_in BETWEEN -20999 AND -20000
5 THEN
6 RAISE_APPLICATION_ERROR (err_in, msg_in);
7 ELSIF err_in > 0 AND err_in NOT IN (1, 100)
8 THEN
9 RAISE_APPLICATION_ERROR (-20000, err_in ||"-"|| msg_in);
10 ELSIF err_in IN (100, -1403)
11 THEN
12 RAISE NO_DATA_FOUND;
13 ELSE
14 DECLARE
15 cur PLS_INTEGER := DBMS_SQL.OPEN_CURSOR;
16 returnValue PLS_INTEGER;
17 BEGIN
18 DBMS_SQL.PARSE (cur, "DECLARE myexc EXCEPTION; PRAGMA EXCEPTION_INIT (myexc, " || TO_CHAR (err_in) || ");" || "BEGIN RAISE myexc; END;",DBMS_SQL.NATIVE);
19 returnValue := DBMS_SQL.EXECUTE (cur);
20 DBMS_SQL.CLOSE_CURSOR (cur);
21 END;
22 END IF;
23 END;
24 /
Procedure created.
SQL>
SQL></source>

== Cursor for update==



<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> DECLARE
2 CURSOR employee_cur IS
3 SELECT * FROM employee
4 FOR UPDATE OF salary;
5 BEGIN
6 FOR employee_rec IN employee_cur
7 LOOP
8 UPDATE employee
9 SET salary = 10000
10 WHERE CURRENT OF employee_cur;
11 END LOOP;
12 END;
13 /
PL/SQL procedure successfully completed.
SQL>
SQL> SELECT * FROM employee;

ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 10000 Toronto Programmer
02 Alison Mathews 21-MAR-76 21-FEB-86 10000 Vancouver Tester
03 James Smith 12-DEC-78 15-MAR-90 10000 Vancouver Tester
04 Celia Rice 24-OCT-82 21-APR-99 10000 Vancouver Manager
05 Robert Black 15-JAN-84 08-AUG-98 10000 Vancouver Tester
06 Linda Green 30-JUL-87 04-JAN-96 10000 New York Tester
07 David Larry 31-DEC-90 12-FEB-98 10000 New York Manager
08 James Cat 17-SEP-96 15-APR-02 10000 Vancouver Tester
8 rows selected.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.</source>

== Cursor FOR UPDATE NOWAIT==



<source lang="sql">
SQL>
SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
2 ENAME VARCHAR2(10),
3 JOB VARCHAR2(9),
4 MGR NUMBER(4),
5 HIREDATE DATE,
6 SAL NUMBER(7, 2),
7 COMM NUMBER(7, 2),
8 DEPTNO NUMBER(2));
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>
SQL>
SQL> DECLARE
2 waitsecs CONSTANT PLS_INTEGER := 10;
3
4 CURSOR emp_cur IS SELECT ename, rowid FROM emp FOR UPDATE NOWAIT;
5 emp_rec emp_cur%ROWTYPE;
6
7 resource_busy EXCEPTION;
8 PRAGMA EXCEPTION_INIT (resource_busy, -54);
9
10 starttime PLS_INTEGER;
11 BEGIN
12 starttime := DBMS_UTILITY.GET_TIME;
13 LOOP
14 BEGIN
15 OPEN emp_cur;
16 EXIT;
17 EXCEPTION
18 WHEN resource_busy
19 THEN
20 IF DBMS_UTILITY.GET_TIME - starttime < waitsecs / 100
21 THEN
22 DBMS_LOCK.SLEEP (1);
23 ELSE
24 RAISE;
25 END IF;
26 END;
27 END LOOP;
28
29 LOOP
30 FETCH emp_cur INTO emp_rec;
31 EXIT WHEN emp_cur%NOTFOUND;
32 UPDATE emp SET sal = sal + 1000 WHERE ROWID = emp_rec.rowid;
33 END LOOP;
34
35 CLOSE emp_cur;
36 COMMIT;
37 END;
38 /
PL/SQL procedure successfully completed.
SQL>
SQL> drop table emp;
Table dropped.
SQL>
SQL></source>

== Using WHERE CURRENT OF==



<source lang="sql">
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>
SQL> DECLARE
2 v_salary employee.salary%TYPE;
3
4 CURSOR c_Registeredemployee IS
5 SELECT *
6 FROM employee
7 WHERE id IN ("01")
8 FOR UPDATE OF salary;
9
10 BEGIN
11 -- Set up the cursor fetch loop.
12 v_salary := 100;
13 FOR v_employeeInfo IN c_Registeredemployee LOOP
14
15
16 -- Update the row we just retrieved from the cursor.
17 UPDATE employee
18 SET salary = salary + v_salary
19 WHERE CURRENT OF c_Registeredemployee;
20 END LOOP;
21
22 -- Commit our work.
23 COMMIT;
24 END;
25 /
PL/SQL procedure successfully completed.
SQL>
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.
SQL>
SQL></source>

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