algorithm - Finding recursive sum in SQL statement -


i've 2 tables , b like: a (id, dep_id) , b (id, amount)

the data in tables this

a                 b  id  dep_id        id   amount --- -------       ---- -------- 1   2             1    100     2   3             2    200 3   null          3    300    4   null          4    400

the id column in table holds id table b. given id in table a, there might dep_id holds id of table b.

the requirement calculate sum of amount of entry in b , of dependent entries. has done in 1 single sql query. can't use pl/sql block that. idea how that.

example:

sum(id=1) = 100(id=1,dep_id=2) + 200(id=2,dep_id=3) + 300(id=3) = 600

you can use connect root build link of dependency (hierarchical query), aggregate:

sql> select id, sum(amount)   2    (select connect_by_root(a.id) id, b.amount   3              4            join b on a.id = b.id   5           start a.id = 1   6           connect prior a.dep_id = a.id)   7   group id;          id sum(amount) ---------- -----------          1         600

additional solutions available on similar more complex schema (for example id:1 needs 4xid:2, needs 8xid:3 each) on this sql quiz on plsqlchallenge.


Comments

Post a Comment

Popular posts from this blog

jquery - How can I dynamically add a browser tab? -

since using iframes house external pages are, accounts "not preferred method" , disallowed sites (flickr, one), want dynamically generate browser tabs. e.g., when user submits form, want dynamically generate tab on browser in response submitted. e.g., might want add new tab url like: http://www.bigsurgarrapata.com/contact how in jquery? you want form target attribute action attribute. http://www.w3schools.com/tags/att_form_target.asp browsers have ultimate control on result of target attribute open new tab value of _blank. <form action="contact_submit.php" target="_blank" method="post">
Read more

node.js - Getting the socket id,user id pair of a logged in user(s) -

i have web application done using node js , in it,i have authentication system requires users log in before can access pages. have 2 pages,the homepage , updates page. from read docs,a new socket id issued when user opens tab in browser. me being admin,i know socket id of logged in user , more so,the socket id,logged in user id pair logged in users. what method can use socket id,logged in user id pair make sure broadcast realtime info users online?.
Read more

keyboard - C++ GetAsyncKeyState alternative -

i using windows.h library's getasynckeystate function define key pushed on keyboard . here program returns int value of pushed key example. #include <iostream> #include <windows.h> using namespace std; int main (){ char i; for(i=8;i<190;i++){ if(getasynckeystate(i)== -32767){ cout<<int (i)<<endl; } } return 0; } but trying make opengl simple game , function appeared slow . there function not need cycle 180 times , if statement . thanks you're trying make opengl game, you're going use glfw. if that's case can away using glfwgetkey() such: if (glfwgetkey(glfw_key_up) == glfw_press) {...} if (glfwgetkey(glfw_key_down) == glfw_press) {...} that method nicely explained in tutorial 6 opengl-tutorial.org . should start first tutorial of beginners tutorials , later intermediate tutorials . if you're going make win32 window can listen wm_keydown or wm_keyup messages , virtua
Read more