I am actually training in oracle SQL basics and I have created a trigger that looks like this one (it works!):
create or replace TRIGGER insert_refereenation
BEFORE INSERT OR UPDATE ON Game
FOR EACH ROW
DECLARE
v_nation_id NUMBER(4) := '';
v_nationname VARCHAR2(100) := '';
BEGIN
SELECT Nation_id
INTO v_nation_id
FROM referre
WHERE referee_id= :new.referee_id;
SELECT Name
INTO v_nationname
FROM Nation
WHERE Nation_id = v_nation_id;
:NEW.referee_nation_name:= v_nationname;
END;
This trigger works fine but I have two simple questions:
Is it possible to write the result from the second SELECT right into the: NEW.referee_nation_name field? So I wouldn´t need the second variable.
Do you see other things which can get optimized?
You could use a join so that you have only one query instead of two, and use the :new.column_name directly in the into clause:
SELECT n.name
INTO :new.referee_nation_name
FROM referee r
JOIN nation n ON r.nation_id = n.nation_id
WHERE r.referee_id = :new.referee_id;
Related
Currently, I have some SQL queries which looks like this:
Drop Table X;
Create Table X(id INTEGER);
Insert Into X
select ..
from..
where a.name = GIVENNAME;
Select SUM(..)
from ..
..
order by date desc;
And I want to put all these into a SQL Function, where I can choose the Parameter "GIVENNAME" when I call the function.
Is there a way to make this possible?
I would know how to do it in JSON/Java, but I have really no clue how to make it as a Function in SQL (using Oracle).
Edit:
After pointing out some things, I want to add my current code:
DROP TABLE TEMPTABLE;
CREATE TABLE TEMPTABLE
(mitID INTEGER);
INSERT INTO TEMPTABLE
select m.mitid
from mitarbeiter m
inner join abteilungen a on m.abt = a.abtid
where a.abtname = #GIVENNAME;
select SUM(g.kosten)
from gehaelter g
left outer join gehaelter k
on g.mitarbeiter = k.mitarbeiter
and g.vondatum < k.vondatum
where k.mitarbeiter is null AND g.mitarbeiter in (select * from TEMPTABLE)
order by g.vondatum desc;
I'm currently more interested in a working solution than a nice & clean one
Fortunately you can have both:
create or replace function get_sum_kosten
( p_givenname in abteilungen.abtname%type )
return number
as
return_value number;
begin
select SUM(g.kosten)
into return_value
from gehaelter g
left outer join gehaelter k
on g.mitarbeiter = k.mitarbeiter
and g.vondatum < k.vondatum
where k.mitarbeiter is null
AND g.mitarbeiter in (select m.mitid
from mitarbeiter m
inner join abteilungen a on m.abt = a.abtid
where a.abtname = P_GIVENNAME
)
;
return return_value;
end;
Possible? Yes. Recommended? No.
For any DDL, you'd have to use dynamic SQL (EXECUTE IMMEDIATE). If queries are complex, those commands will be difficult to maintain.
INSERT is a DML, but you can't use it in a function, unless it is an autonomous transaction (and you'll have to commit (or rollback) within the function).
If it were a procedure, you'd - at least - avoid the last problem I mentioned. If you're returning something, use an OUT parameter.
Can't you use a (global) temporary table, instead? Create it once, use it many times. I understand that your code might be very complex and maybe it really can't fit into a single SELECT statement, but you should - at least - try to do that job in an Oracle spirit (i.e. it is not MS SQL Server).
example of procedure
https://www.sitepoint.com/stored-procedures-mysql-php/
like this
DELIMITER $$
CREATE PROCEDURE `avg_sal`(out avg_sal decimal)
BEGIN
select avg(sal) into avg_sal from salary;
END
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 have an oracle sql stored procedure that returns a cursor.
This cursor gets in the stored procedure body the value of a complex select statement (in the example below I made the select statement simple).
Then, I want to use the cursor for two things:
1. Use it as return value of the stored procedure
2. Use its data to update some values in another table within the stored procedure body
I couldn't find how to do it, so in the meanwhile I had to replicate the (complex) select statement and let another cursor have its value for updating the other table.
create or replace procedure sp_GetBuildings(returned_cursor OUT SYS_REFCURSOR,
timeFrameHrsParam number) is
v_buildingID Buildings.buildingId%type;
cursor t_result is
select customerId
from (select buildingId from Buildings) b
inner join Customers c on c.building_id = b.building_id;
begin
open returned_cursor for
select customerId
from (select buildingId from Buildings) b
inner join Customers c on c.building_id = b.building_id;
for t in t_result
loop
v_buildingID := t.building_id;
update Buildings set already = 1 where building_id = v_buildingID ;
end loop;
commit;
end sp_GetBuildings;
Can you help me with a solution that will save me the select statement replication?
You can't copy or clone a cursor in Oracle. The cursor is just a pointer to the result set and reading the cursor moves along the result list in a single direction. However, you can achieve something very similar using arrays:
CREATE TYPE nt_number AS TABLE OF NUMBER;
CREATE OR REPLACE PROCEDURE sp_getbuildings(returned_table OUT nt_number,
timeframehrsparam NUMBER) IS
CURSOR t_result IS
SELECT customerid
FROM buildings b
JOIN customers c
ON c.building_id = b.building_id;
i NUMBER;
BEGIN
OPEN t_result;
FETCH t_result
BULK COLLECT INTO returned_table;
CLOSE t_result;
FORALL i IN returned_table.FIRST .. returned_table.LAST
UPDATE buildings
SET already = 1
WHERE building_id = v_buildingid;
COMMIT;
END sp_getbuildings;
I'm changing a database (oracle) with a script containing a few updates looking like:
UPDATE customer
SET status = REPLACE(status, 'X_Y', 'xy')
WHERE status LIKE '%X_Y%'
AND category_id IN
(SELECT id
FROM category
WHERE code = 'ABC');
UPDATE customer
SET status = REPLACE(status, 'X_Z', 'xz')
WHERE status LIKE '%X_Z%'
AND category_id IN
(SELECT id
FROM category
WHERE code = 'ABC');
-- More updates looking the same...
In this case, how would you enforce DRY (Don't Repeat Yourself)?
I'd particularly interested in solving the two following recurring problems:
Define a function, available from this script only, to extract the subquery SELECT id FROM category WHERE code = 'ABC'
Create a set of replace rules (that could look like {"X_Y": "yx", "X_Z": "xz", ...} in a popular programming language) and then iterate a single update query on it.
Thanks!
I would reduce it to a single query:
UPDATE customer
SET status = REPLACE(REPLACE(status, 'X_Y', 'xy'), 'X_Z', 'xz')
WHERE status REGEXP_LIKE 'X_[YZ]'
AND category_id IN
(SELECT id
FROM category
WHERE code = 'ABC');
First of all, remember that scripting is not the same thing as programming, and you don't have to adhere to DRY principles. Scripts like this one are usually one-offs, not a program to be maintained over a long time.
But you could use PL/SQL to do this:
declare
type str_tab is table of varchar2(30) index by binary_integer;
from_tab str_tab;
to_tab str_tab;
begin
from_tab(1) := 'X_Y';
from_tab(2) := 'X_Z';
to_tab(1) := 'xy';
to_tab(2) := 'xz';
for i in 1..from_tab.count loop
UPDATE customer
SET status = REPLACE(status, from_tab(i), to_tab(i))
WHERE status LIKE '%' || from_tab(i) || '%'
AND category_id IN
(SELECT id
FROM category
WHERE code = 'ABC');
end loop;
end;
Pretty straightforward, unless I'm missing something.
UPDATE customer
SET status = REPLACE(REPLACE(status,'X_Y','xy'),'X_Z','xz')
WHERE ( status LIKE '%X_Y%' Or status LIKE '%X_Z%')
AND category_id IN
(SELECT id
FROM category
WHERE code = 'ABC');
Write a script that takes parameters and call it multiple times. (I'm assuming you're using SQLPlus to run the script.)
replace_in_status.sql:
UPDATE customer
SET status = REPLACE(status, UPPER('&1'), '&2')
WHERE status LIKE '%' ||UPPER('&1')|| '%'
AND category_id IN
(SELECT id
FROM category
WHERE code = 'ABC');
Calling script:
#replace_in_status X_Y xy
#replace_in_status X_Z xz
Okay, a shot from the hip here, take it easy on my syntax :-)
Would an approach like this help:
DECLARE
v_sql1 VARCHAR2(1000);
v_sql2 VARCHAR2(2000);
TYPE T_Rules IS RECORD (srch VARCHAR2(100), repl(VARCHAR2(100));
TYPE T_RuleTab IS TABLE OF T_Rules INDEX BY BINARY_INTEGER;
v_rules T_RuleTab;
FUNCTION get_subquery RETURN VARCHAR2 IS
BEGIN
RETURN '(SELECT id FROM category WHERE code = ''ABC'')';
END;
BEGIN
v_sql1 := 'UPDATE customer SET status = REPLACE('':1'','':2'') WHERE status LIKE ''%:1%'' AND category_id IN ';
v_rules(1).srch := ('X_Y'); v_rules(1).repl := 'yx';
v_rules(2).srch := ('X_Z'); v_rules(2).repl := 'xz';
FOR i IN 1..v_rules.COUNT LOOP
v_sql2 := v_sql1||get_subquery();
EXECUTE IMMEDIATE v_sql2 USING v_rules(i).srch, v_rules(i).repl;
END LOOP;
END;
You could replace the PL/SQL table with a real table and run a cursor over it, but this addresses your second requirement.
Obviously some work is left on get_subquery, your first requirement ;-)
EDIT
Dang! forgot to mention you need to be careful with that replace string in your WHERE clause - underscores are a single character matching wild card in Oracle...
Depending on how important the script is, I would:
Just copy and paste and modify, or
Write a script in another programming language that has better ways to resolve the duplication.
For the replace rules you could create a temporary table and fill it with these replace rules, and then join with this table.
If the subquery is always the same, you have solved the first problem also by using a join.
I've seen a few approaches to this:
Use string buffers to assemble the sql dynamically using PL/SQL or in your programming language.
Use a framework such as IBATIS which let's you reuse and extend fragments of SQL that are stored in XML files.
Using an ORM framework circumvents this issue by working with objects rather than directly with the SQL.
Depending on your language and problem at hand using a framework may be the best approach and then extending it to do what you want it to do.
The solution suggested by soulmerge is the simplest, and therefore best one - you just need to nest the calls to "replace". I just want to add that the condition
status like '%tagada%'
is useless. replace() will change nothing to the status if the searched string is not found, therefore you can safely apply it to all rows. And since a condition where you search a string lost in the middle of another string cannot make any use of whatever index you have, it's useless as a filtering condition.
Your only filtering condition is the one on category_id ...
Which brings one point that justifies why soulmerge's solution is best: iterating on all the changes is a bad idea. Suppose that the filter on category_id is moderately selective, odds are that Oracle will choose to scan the table. Do you really want to scan the table each time when you can do all the changes in a single pass?