self-join Questions
15
Solved
I don't understand the need for self-joins. Can someone please explain them to me?
A simple example would be very helpful.
7
Solved
What is the simplest way of doing a recursive self-join in SQL Server?
PersonID | Initials | ParentID
1 CJ NULL
2 EB 1
3 MB 1
4 SW 2
5 YT NULL
6 IS 5
I want to be able to get the records only rela...
Amil asked 18/11, 2009 at 16:29
4
Solved
Does it get any simpler than this query?
delete a.* from matches a
inner join matches b ON (a.uid = b.matcheduid)
Yes, apparently it does... because the performance on the above query is really...
Sosthenna asked 17/8, 2011 at 5:47
3
Solved
I have a component list made of 3 columns: product, component and quantity of component used:
a <- structure(list(prodName = c("prod1", "prod1", "prod2", "prod3",
"prod3", "int1", "int1", "int...
Paulinepauling asked 30/6, 2019 at 2:39
2
Solved
I have a self-join for my model in ActiveRecord, as follows:
class Employee < ActiveRecord::Base
has_many :subordinates, class_name: "Employee",
foreign_key: "manager_id"
belongs_to :manag...
Distil asked 12/8, 2015 at 18:44
6
Solved
I am trying to get some rows from the same table. It's a user table: user has user_id and user_parent_id.
I need to get the user_id row and user_parent_id row. I have coded something like this:
...
0
In the project I´m working there is a part of the database that is like the following diagram
The domain classes have a definition similar to the following:
class File{
String name
}
class Do...
Oleta asked 10/10, 2017 at 19:14
1
Solved
While preparing an answer to the question dplyr or data.table to calculate time series aggregations in R I noticed that I do get different results depending on whether the table is updated in place...
Denominational asked 21/8, 2017 at 8:47
4
Solved
I have a table:
Parent Child Educated
'P1', 'C1', 'YES'
'P1', 'C2', 'YES'
'P1', 'C3', 'NO'
'P2', 'C11', 'YES'
'P2', 'C12', 'NO'
'P3', 'C21', 'YES'
'P3', 'C22', 'YES'
'P4', 'C31', 'NO'
'P4', 'C32',...
1
Solved
I am trying to query in SQL and I can not resolve it.
I have a table tCliente:
What I want to do is a JOIN with the same table to find each pair of clients that lives in the same city.
I try to...
6
I've got a table of people - an ID primary key and a name. In my application, people can have 0 or more real-world relationships with other people, so Jack might "work for" Jane and Tom might "repl...
Revert asked 1/5, 2010 at 18:47
2
Solved
What would I seek to achieve from a self-join?
I already know what a self-join does. Operational descriptions on Stack Overflow with tables or join lists or the self-referencing employee-manager ex...
Desma asked 1/4, 2016 at 9:9
4
Solved
Here is my testing table data:
Testing
ID Name Payment_Date Fee Amt
1 BankA 2016-04-01 100 20000
2 BankB 2016-04-02 200 10000
3 BankA 2016-04-03 100 20000
4 BankB 2016-04-04 300 20000
I am try...
Eleanor asked 22/4, 2016 at 1:22
7
Solved
I have the following tables:
Employees
-------------
ClockNo int
CostCentre varchar
Department int
and
Departments
-------------
DepartmentCode int
CostCentreCode varchar
Parent int
Departmen...
Cassaundra asked 15/4, 2016 at 12:44
1
Given a table named rating in a MySQL database.
+-------------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+-----...
2
I would like to know if i can convert this criteria into a detached criteria. I am not understanding detached criteria correctly. can some one help.
Criteria crit = sessionC.createCriteria(OP_DOCT...
Griswold asked 16/2, 2016 at 5:47
6
Suppose I have a table consisting of entries like
ID Arrival Date Arrival City Departure Date Departure City
1 Jun 27 2015 Berlin Jun 20 2015 Paris
1 Jul 1 2015 Rome Jun 29 2015 Berlin
1 Jul 30 20...
Mores asked 15/1, 2016 at 16:45
2
I have a page table. Pages can have parents, which are also pages. I want to select all pages with parent_id = NULL and their 'children'. But when I try this
public function getPages()
{
return $...
Matri asked 17/6, 2015 at 19:14
3
Solved
I need to use Self Join on this table.
+------------+------+--------+
| Country | Rank | Year |
+------------+------+--------+
|France | 55 | 2000 |
+------------+------+--------+
|Canada | 30 | 2...
1
I have a table in an oracle database. The schema is
create table PERIODS
(
ID NUMBER,
STARTTIME TIMESTAMP,
ENDTIME TIMESTAMP,
TYPE VARCHAR2(100)
)
I have two different TYPE's: TYPEA and...
Niacin asked 1/8, 2015 at 20:27
3
With a 2-column data.table, I'd like to summarize the pairwise relationships in column 1 by summing the number of shared elements in column 2. In other words, how many shared Y elements does each p...
Allamerican asked 27/2, 2015 at 9:39
1
5
Solved
Consider the following table:
mysql> select * from phone_numbers;
+-------------+------+-----------+
| number | type | person_id |
+-------------+------+-----------+
| 17182225465 | home | 1 |
...
1
Solved
I am trying to do a join of a data.table with itself.
The condition to join is based on the value of a column (not the key) being used to access a matrix.
Each row has a date(in seconds) and record...
Slaty asked 17/3, 2015 at 13:54
3
Solved
Given the following data.table with financial data:
userId systemBankId accountId valueDate quantity description
871 0065 6422 2013-02-28 -52400 AMORTIZACION PRESTAMO
871 0065 6422 2013-03-28 -52...
Arakawa asked 10/3, 2015 at 15:15
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