Let us assume we have a request to show results from a query that is too massive to run on-line. Let us also assume that we may distinguish in this query a series on countries \/ persons that must be run.<\/p>\n\n\n\n
In pseudo code, we have the situation that we may have to run: select * from complicated that could be translated into something like: for employees select * from lesscomplicated(employee). <\/p>\n\n\n\n
This can be solved in a PLSQL programme that contains a LOOP. Two possible solutions are given below:<\/p>\n\n\n\n
create or replace PROCEDURE FORLOOP AS
CURSOR c1 IS SELECT * FROM HR.EMPLOYEES;
i NUMBER:= 0;
v_totalName varchar2(80);
BEGIN
FOR e_rec IN c1 LOOP
i:= i+1;
select DEPARTMENTS.department_name into v_totalName from HR.DEPARTMENTS where e_rec.department_id = DEPARTMENTS.department_id;
dbms_output.put_line(i||chr(9)||e_rec.EMPLOYEE_ID||chr(9)||e_rec.LAST_NAME||chr(9)|| v_totalName);
END LOOP;
END;<\/pre>\n\n\n\nThe idea is that we have a series of employees. For each of these employees, we have a simple query for one employee. This simple query for one employee runs fast. The loop guarantees that all employees are considered and all results are returned. A<\/p>\n\n\n\n
An alternative programme is:<\/p>\n\n\n\n
create or replace PROCEDURE FORLOOP AS
CURSOR c1 IS SELECT * FROM HR.EMPLOYEES;
e_rec c1%ROWTYPE;
i NUMBER:= 0;
v_totalName varchar2(80);
BEGIN
OPEN c1;
i:=0;
LOOP
FETCH c1 into e_rec;
EXIT WHEN c1%NOTFOUND;
i:= i+1;
select DEPARTMENTS.department_name into v_totalName from HR.DEPARTMENTS where e_rec.department_id = DEPARTMENTS.department_id;
dbms_output.put_line(i||chr(9)||e_rec.EMPLOYEE_ID||chr(9)||e_rec.LAST_NAME||chr(9)|| v_totalName);
END LOOP;
END;<\/pre>\n","protected":false},"excerpt":{"rendered":"Let us assume we have a request to show results from a query that is too massive to run on-line. Let us also assume that we may distinguish in this query a series on countries \/ persons that must be run. In pseudo code, we have the situation that we may have to run: select […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-2996","post","type-post","status-publish","format-standard","hentry","category-nice-to-know"],"_links":{"self":[{"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/posts\/2996","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2996"}],"version-history":[{"count":0,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/posts\/2996\/revisions"}],"wp:attachment":[{"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2996"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2996"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2996"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}