I have a cursor as below:
CURSOR employee_cur IS
SELECT * FROM employee where department_id='accounts';
I need to modify the data for some specific rows inside the cursor only. Later on whoever will use this cursor, they should find the modified data only, from this cursor.
I don't want to update any DB table. Can anybody help me on this?
You can't.
A cursor is a read-only structure. It is a pointer to a SQL statement. When that SQL statement is executed, the data will be fetched from the database. You can manipulate the data in the SELECT statement itself as much as you would like. But you can't modify the data that the cursor will return once the cursor is opened.
You can, of course, manipulate the data in the SELECT statement. For example, your query can do something like
SELECT employee_id,
first_name,
last_name,
(CASE WHEN last_name = 'King'
THEN salary*2
ELSE salary
END) salary
FROM employee
to double any employee named "King"'s salary in the result set. You can use a UNION ALL to return rows that don't exist in the database, i.e.
SELECT employee_id,
first_name,
last_name,
salary
FROM employee
UNION ALL
SELECT -1,
'Justin',
'Cave',
17
FROM dual
The simplest way to get you're trying to achieve is to return either varray or nested table (pipelined or by out param). When you're populate it you could to do all changes you need. If you really need to return a cursor and do not need something like UPDATE CURRENT OF you could put data in varray/nested table, past as the IN param into pipilined function and create cursor as select * from your pipilened function(prepared vararray/nested table).
You could do all treatment inside your function, put results at any temporary table and return the cursor from the temporary table.
Declare a collection-
type my_emp_table_type is table of employee%rowtype;
myEmpTable my_emp_table_type;
And then use BULK COLLECT to collect the cursor data, by
SELECT * BULK COLLECT INTO myEmpTable
FROM employee
WHERE department_id='accounts';
Modify collection elements like-
myEmpTable(10).id := 10;
myEmpTable(10).first_name := 'John';
myEmpTable(10).last_name := 'Doe';
And use myEmpTable wherever you want.
Note, you can loop through the collection as
for i in myEmpTable.first .. myEmpTable.last loop
if myEmpTable.(i)last_name = 'Doe'
then
myEmpTable.(i)sal := 50000;
end if;
...
....
end loop;
Related
I have a created a procedure as
create or replace procedure availability(num in number) as
begin
delete from vehicle_count;
insert into vehicle_count from select engine_no,count(engine_no)
from vehicle
where engine_no = num
group by engine_no;
end;
/
The procedure was created successfully but now i have to write a separate query to view the contents of vehicle_count as
select * from vehicle_count;
I tried inserting the select statement into the procedure after insertion but it showed a error stating "an INTO clause is expected in the select statement".
How can I create procedure to select the required contents and display it in a single execute statement?
Table schema
vehicle(vehicle_no,engine_no,offence_count,license_status,owner_id);
vehicle_count(engine_no,engine_count);
Check this (MS SQL SERVER)-
create or alter procedure availability(#num as int) as
begin
delete from vehicle_count;
insert into vehicle_count
output inserted.engine_no,inserted.count_engine_no
select engine_no,count(engine_no) as count_engine_no
from vehicle
where engine_no=#num
group by engine_no;
end;
If you want to use a SELECT into a PL/SQL block you should use either a SELECT INTO or a loop (if you want to print more rows).
You could use something like this:
BEGIN
SELECT engine_no, engine_count
INTO v_engine, v_count
FROM vehicle_count
WHERE engine_no = num;
EXCEPTION
WHEN NO_DATA_FOUND THEN
v_engine := NULL;
v_count := NULL;
END;
v_engine and v_count are two variables. You can declare them in your procedure, and they will contain the values you want to print.
You said that the procedure you wrote (actually, you posted here) compiled successfully. Well, sorry to inform you - that's not true. This is not a valid syntax:
insert into vehicle_count from select engine_no,count(engine_no)
----
from? Here?
Consider posting true information.
As of your question (if we suppose that that INSERT actually inserted something into a table):
at the beginning, you delete everything from the table
as SELECT counts number of rows that share the same ENGINE_NO (which is equal to the parameter NUM value), INSERT inserts none (if there's no such NUM value in the table) or maximum 1 row (because of aggregation)
therefore, if you want to display what's in the table, all you need is a single SELECT ... INTO statement whose result is displayed with a simple DBMS_OUTPUT.PUT_LINE which will be OK if you're doing it interactively (in SQL*Plus, SQL Developer, TOAD and smilar tools). Regarding table description, I'd say that ENGINE_NO should be a primary key (i.e. that not more than a single row with that ENGINE_NO value can exist in a table).
create or replace procedure availability (num in number) as
l_engine_no vehicle_count.engine_no%type;
l_engine_count vehicle_count.engine_count%type;
begin
delete from vehicle_count;
insert into vehicle_count (engine_no, engine_count)
select engine_no, count(engine_no)
from vehicle
where engine_no = num
group by engine_no;
-- This query shouldn't return TOO-MANY-ROWS if ENGINE_NO is a primary key.
-- However, it might return NO-DATA-FOUND if there's no such NUM there, so you should handle it
select engine_no, engine_count
into l_engine_no, l_engine_count
from vehicle_count
where engine_no = num;
dbms_output.put_line(l_engine_no ||': '|| l_engine_count);
exception
when no_data_found then
dbms_output.put_line('Nothing found for ENGINE_NO = ' || num);
end;
/
There are numerous alternatives to that (people who posted their answers/comments before this one mentioned some of those), and the final result you'd be satisfied with depends on where you want to display that information.
This is a simplified version of what I'm trying to do, but let's say I want to select all employees whose manager is in a given department. I could have a SQL query like the following:
SELECT employees.id
FROM employees
WHERE employees.manager IN (SELECT managers.id
FROM managers
WHERE managers.dept = 12)
;
But let's say I want to abstract the manager subquery into a PL/SQL subprogram. How do I do that?
The stored procedures I've worked with (which are mostly written by other developers) tend to have out parameters that get mapped by PHP calling code into a PHP array. I don't really have any experience of calling one stored procedure from another.
What I'd like to do is to have something like this:
SELECT employees.id
FROM employees
WHERE employees.manager IN my_stored_procedure(12)
;
and then my_stored_procedure would output the set of manager IDs for the input parameter (which is 12 in this example).
It is not possible to do exactly as you have posted, but if the selection of managers are not straightforward, you could abstract it through a view or make use of a function that returns a table, like this:
SELECT employees.id
FROM employees
WHERE employees.manager IN (SELECT * from TABLE(get_managers_from_dept(12)));
In this link there is an example of that approach:
Function or Procedure for an IN clause
To Call A stored Proc from another Stored Proc you just need to call it from the Main Proc as mentioned below. This Main Proc can be called /initiated by a PHP Code.
PROCEDURE some_sp
AS
BEGIN
some_other_sp('parm1');
END;
Although less straight-forward, You can do accomplish it by using dynamic sql. This is the structure of your stored procedure. It returns a comma separated list of manager_ids for a given department.
CREATE OR REPLACE FUNCTION my_stored_procedure(
p_dept NUMBER)
RETURN VARCHAR2
IS
v_manager_list VARCHAR2(1000);
BEGIN
SELECT m.id INTO v_manager_list FROM managers m WHERE m.dept = p_dept;
RETURN '('||v_manager_list||')';
EXCEPTION
WHEN NO_DATA_FOUND THEN
RETURN '(NULL)';
END;
/
Now you cannot use this to directly query as ...IN my_stored_procedure(12),
rather you must use a dynamic fetch into a collection.
SET SERVEROUTPUT ON;
DECLARE
TYPE v_emp_type
IS
TABLE OF employees.id%TYPE;
v_emp v_emp_type;
BEGIN
EXECUTE IMMEDIATE 'SELECT employees.id
FROM employees
WHERE employees.id IN '|| my_stored_procedure(100) BULK COLLECT INTO v_emp ;
FOR i IN v_emp.FIRST..v_emp.LAST
LOOP
DBMS_OUTPUT.PUT_LINE(v_emp(i));
END LOOP;
END;
/
I'm trying to get a procedure that will allow me to get data from a column and insert it into two different columns in a different table. the first table currently has both first and last name in a single column. I have another table with first name and last name in different columns and I need to separate and insert them from Column1/Table1 into the two columns in Table2 preferably using a procedure since I have a lot of names to migrate.
Column1(Name) in Table 1 looks like this
NAME
First_Name1 Last_name1
First_Name2 Last_Name2
First_Name3 Last_Name3
And I need the data to be separated like this in Table2 as FName/LName using the data from the first table:
F_Name | L_Name
First_Name1|Last_Name1
First_Name2|Last_Name2
First_Name3|Last_Name3
I figured out how to get the data from the last and the first name separated using SUBSTR and INSTR, but I can't figure out how to put this inside a Procedure, or how to Loop it since I want to use it for several rows.
select substr(staff.name, 0, instr(staff.name, ' ')-1) as Fname
from staff;
select substr(staff.name, instr(staff.name,' ')+1) as Lname
from Staff;
Any ideas/Help? Thanks guys.
Building a Looping PL/SQL Based DML Cursor For Multiple DML Targets
A PL/SQL Stored Procedure is a great way to accomplish your task. An alternate approach to breaking down your single name field into FIRST NAME and LAST NAME components could be to use an Oracle Regular Expression, as in:
SELECT REGEXP_SUBSTR('MYFIRST MYLAST','[^ ]+', 1, 1) from dual
-- Result: MYFIRST
SELECT REGEXP_SUBSTR('MYFIRST MYLAST','[^ ]+', 1, 2) from dual
-- Result: MYLAST
A procedure based approach is a good idea; first wrap this query into a cursor definition. Integrate the cursor within a complete PL/SQL stored procedure DDL script.
CREATE or REPLACE PROCEDURE PROC_MYNAME_IMPORT IS
-- Queries parsed name values from STAFF (the source) table
CURSOR name_cursor IS
SELECT REGEXP_SUBSTR(staff.name,...) as FirstName,
REGEXP_SUBSTR(... ) as LastName
FROM STAFF;
BEGIN
FOR i IN name_cursor LOOP
--DML Command 1:
INSERT INTO Table_One ( first_name, last_name )
VALUES (i.FirstName, i.LastName);
COMMIT;
--DML Command 2:
INSERT INTO Table_Two ...
COMMIT;
END LOOP;
END proc_myname_import;
As you can see from the example block, a long series of DML statements can take place (not just two) for a given cursor record and its values as it is handled by each loop iteration. Each field may be referenced by the name assigned to them within the cursor SQL statement. There is a '.' (dot) notation where the handle assigned to the cursor call is the prefix, as in:
CURSOR c1 IS
SELECT st.col1, st.col2, st.col3
FROM sample_table st
WHERE ...
Then the cursor call for looping through the main record set:
FOR my_personal_loop IN c1 LOOP
...do this
...do that
INSERT INTO some_other_table (column_one, column_two, column_three)
VALUES (my_personal_loop.col1, my_personal_loop.col2, ...);
COMMIT;
END LOOP;
... and so on.
This should work for you.
insert into newtable(FirstName, LastName)
select substr(staff.name, 0, instr(staff.name, ' ') - 1),
substr(staff.name, instr(staff.name, ' ') + 1)
from staff;
I am new to this group. I was trying to think of having a cursor with condition select statement.
Some how like this pseudo code--
[B]cursor test_cursor is
if condition == 't11'
then
select * from test1;
else
select * from test1;
end if;[/B]
begin
for cursorVal in test_cursor loop
//Doing the actual task on cursor data.
end loop;
commit;
end;
Actually, i came across with a scenario where need to work on two different tables with same DDL.
Based on some user input, need to fetch data from either of the table and further manipulate in procedure. As i said both table are of same DDL
so don't want to create two different cursor. The reason for this same business logic will be applied on both tables data. Its just the user input which decide which table need to fetch data. Some how one can think of this as latest data and historical data and the way DB is designed.
Hope i am clear with my scenario.
Thanks,
Arfeen.
The cursor can be declared as a union as described below. Depending on the content of variable condition, the cursor will either be based on Test1 or Test2.
SELECT * FROM Test1 WHERE condition = 't1'
UNION ALL
SELECT * FROM Test2 WHERE condition = 't2'
What you are trying to achieve looks like it could either be achieved by better table or view design or by using a BULK COLLECT.
If you can - always consider database design first over code.
BEGIN
if condition == 't11' then
SELECT XXXXXX
BULK COLLECT INTO bulk_collect_ids
FROM your_table1;
else
SELECT XXXXXX
BULK COLLECT INTO bulk_collect_ids
FROM your_table2;
end if;
FOR indx IN 1 .. bulk_collect_ids.COUNT
LOOP
.
//Doing the actual task on bulk_collect_ids data.
.
END LOOP;
END;
I'm doing some testing to see if I can speed up a particular result set, but can't seem to get this particular solution working. I have data coming a few different tables and want to combine the data. I want to try this without using a union select to see if I get a performance improvement.
When I have a custom table/object type in a function, it seems to delete the existing data from the table when doing the subsequent select. Is there a way to do subsequent selects into the table without having the previous data deleted?
SQL Fiddle
I don't think that approach will be faster, in fact I expect it to be much slower.
But if you do want to do it, you need to put the rows from the second select into an intermediate collection and then join both using multiset union.
Something like this:
create or replace function
academic_history(p_student_id number)
return ah_tab_type
is
result ah_tab_type;
t ah_tab_type;
begin
select ah_obj_type(student_id,course_code,grade)
bulk collect into result
from completed_courses
where student_id = p_student_id;
select ah_obj_type(student_id,course_code,'P')
bulk collect into T
from trans_courses
where student_id = p_student_id;
result := result multiset union t;
return result;
end;
/
As well as the multiset approach, if you really wanted to do this you could also make it a pipelined function:
create or replace function
academic_history(p_student_id number)
return ah_tab_type pipelined
is
T ah_tab_type;
begin
select ah_obj_type(student_id,course_code,grade)
bulk collect
into T
from completed_courses
where student_id = p_student_id;
for i in 1..T.count loop
pipe row (T(i));
end loop;
select ah_obj_type(student_id,course_code,'P')
bulk collect
into T
from trans_courses
where student_id = p_student_id;
for i in 1..T.count loop
pipe row (T(i));
end loop;
return;
end;
SQL Fiddle.
Thanks a_horse_with_no_name for pointing out that doing the multiple selects one at a time will probably be slower. I was able to reduce the execution time by filtering each select by student_id and then union-ing (rather than union-ing everything then filtering). On the data set I'm working with this solution was the fastest taking less than 1/10 of a second...
create or replace function
academic_history(p_student_id number)
return ah_tab_type
is
T ah_tab_type;
begin
select ah_obj_type(student_id,course_code,grade)
bulk collect
into T
from (
select student_id,course_code,grade
from completed_courses
where student_id = p_student_id
union
select student_id,course_code,'P'
from trans_courses
where student_id = p_student_id);
return T;
end;
/
select *
from table(academic_history(1));
and this took 2-3 seconds to execute...
create view vw_academic_history
select student_id,course_code,grade
from completed_courses
union
select student_id,course_code,'P'
from trans_courses;
select *
from vw_academic_history
where student_id = 1;
SQLFiddle.