self-join Questions
3
Solved
I've got two tables in MS Access that keep track of class facilitators and the classes they facilitate. The two tables are structured as follows:
tbl_facilitators
facilID -> a unique autonumbe...
Osborn asked 29/12, 2014 at 1:2
1
I would like to create a structure of Users having many friends, also of class User:
class User < ActiveRecord::Base
has_and_belongs_to_many :friends, class_name: "User"
end
I do not need an...
Shed asked 4/11, 2013 at 15:17
2
Solved
I'm trying to get the top row by a group of three variables using a data.table.
I have a working solution:
col1 <- c(1,1,1,1,2,2,2,2,3,3,3,3)
col2 <- c(2000,2000,2001,2001,2000,2000,2001,20...
Venita asked 2/4, 2013 at 23:9
2
Solved
I have a table instructors with the following strcture/data:
-----------------
|id | name |
-----------------
|1 | saad |
|2 | imran |
-----------------
I want to do a join with the same table w...
4
Solved
I'm trying to find duplicate rows based on mixed columns. This is an example of what I have:
CREATE TABLE Test
(
id INT PRIMARY KEY,
test1 varchar(124),
test2 varchar(124)
)
INSERT INTO TEST (...
1
Solved
I have a query requirement from ----. Trying to solve it with CONNECT BY, but can't seem to get the results I need.
Table (simplified):
create table CSS.USER_DESC (
USER_ID VARCHAR2(30) not n...
Schofield asked 14/10, 2012 at 20:44
2
Solved
Im trying to calculate the amount of money won by all the offspring of a male race horse (Sire) over a time period. Listed by the Sire with the most amount of money won.
I run the query and get the...
3
Solved
Could anyone advice on how do I improve the performance of the following query. Note, the problem seems to be caused by where clause.
Data (table contains a huge set of rows - 500K+, the set of pa...
Manouch asked 11/9, 2012 at 22:8
2
Solved
It is common task to make some evaluation on pairs of items:
Examples: de-duplication, collaborative filtering, similar items etc
This is basically self-join or cross-product with the same source o...
3
Solved
I have this data in a table, for instance,
id name parent parent_id
1 add self 100
2 manage null 100
3 add 10 200
4 manage null 200
5 add 20 300
6 manage null 300
How can I left join or inner jo...
Vogeley asked 22/3, 2012 at 15:4
1
Solved
I'm using EclipseLink 2.3.1 to model self referencing table with JPA 2.
I get weird warning from EclipseLink when I create the EntityManager.
[EL Warning]: 2011-11-27 14:28:00.91--ServerSession(85...
Farce asked 27/11, 2011 at 12:52
1
Solved
Possible Duplicate:
combinations (not permutations) from cross join in sql
I've currently got a table with the following records:
A1
A2
A3
B1
B2
C1
C2
Where the same letter denotes...
1
Solved
If I have a table that I'd like to cross join to itself, how can I remove the duplicate rows? Or to put it another way, how can I do a "order doesn't matter" cross join?
So for example, if I have ...
Thisbe asked 18/8, 2011 at 18:48
4
Solved
I am trying to implement multiple relations between records of the same model via self-joins (based on @Shtééf's answer). I have the following models
create_table :relations, force: true do |t|
t...
Despoliation asked 14/6, 2011 at 22:51
1
Solved
I have a User that can have collection of users he likes...
Another user can have collection of users he likes....
If User A likes User B and if User B likes User A, then they get to hang out. I ...
Cecillececily asked 17/6, 2011 at 9:4
1
Solved
Given the following tables:
Student
+----+-------+
| id | Name |
+----+-------+
| 1 | Chris |
| 2 | Joe |
| 3 | Jack |
+----+-------+
Enrollment
+---------------+------------+-----------+-----...
5
What I'm doing
I am creating an SQL table that will provide the back-end storage mechanism for complex-typed objects. I am trying to determine how to accomplish this with the best performance. I n...
Homebrew asked 23/2, 2011 at 14:13
1
Solved
So, I'm working on an app where I want to users to be able to group objects in "folders". Basically:
User has_many :foos
Foos don't have to be in a folder, but they can be. In that case:
Folder ...
Urgency asked 24/2, 2011 at 20:12
1
Solved
Class members holds members and within that class is a List<Sessions>. The members I have in a List also.
I have 2 members and each member has a number of sessions. I wish to only return each...
Saponify asked 17/2, 2011 at 9:14
2
Solved
I have an Entity model and I want to display connections between the Entities. ie, Entity 1 is connected to Entity 2.
My thinking, right now, is to create a join model between the two called Conne...
Tautog asked 18/1, 2011 at 18:1
2
Solved
I have an ActiveRecord called Name which contains names in various Languages.
class Name < ActiveRecord::Base
belongs_to :language
class Language < ActiveRecord::Base
has_many :names
Fi...
Impatience asked 4/9, 2010 at 11:15
5
Solved
What is self join and when would you use it? I don't understand self joins so a layman explanation with an example would be great.
1
Solved
I have the following table:
myTable:
+----+----------+
| id | parentID |
+----+----------+
| 1 | null |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
-----------------
i would like to get all rows tra...
Altdorf asked 18/7, 2010 at 15:36
2
Solved
I have a table like
Employee
==================
name salary
==================
a 10000
b 20000
c 5000
d 40000
i want to get all the employee whose salary is greater than A's salary.
I don't want...
1
Solved
I have an existing InnoDB table which already has foreign keys pointing to different tables.
But when I try to create a foreign key pointing to the Primary index, I get an error (check data type)....
Chlamydospore asked 23/3, 2009 at 20:9
© 2022 - 2024 — McMap. All rights reserved.